[v5,1/3] dma: at_xdmac: creation of the atmel eXtended DMA Controller driver

Commit Message

Ludovic Desroches Sept. 22, 2014, 1:22 p.m. UTC

New atmel DMA controller known as XDMAC, introduced with SAMA5D4
devices.

Signed-off-by: Ludovic Desroches <[e-mail]>
---
 drivers/dma/Kconfig            |    7 +
 drivers/dma/Makefile           |    1 +
 drivers/dma/at_xdmac.c         | 1491 ++++++++++++++++++++++++++++++++++++++++
 include/dt-bindings/dma/at91.h |   25 +
 4 files changed, 1524 insertions(+)
 create mode 100644 drivers/dma/at_xdmac.c

Comments

Nicolas Ferre Sept. 22, 2014, 1:42 p.m. UTC | #1

On 22/09/2014 15:22, Ludovic Desroches :
> New atmel DMA controller known as XDMAC, introduced with SAMA5D4
> devices.
> 
> Signed-off-by: Ludovic Desroches <[e-mail]>

It seems good: thanks!

Acked-by: Nicolas Ferre <[e-mail]>

Bye,

> ---
>  drivers/dma/Kconfig            |    7 +
>  drivers/dma/Makefile           |    1 +
>  drivers/dma/at_xdmac.c         | 1491 ++++++++++++++++++++++++++++++++++++++++
>  include/dt-bindings/dma/at91.h |   25 +
>  4 files changed, 1524 insertions(+)
>  create mode 100644 drivers/dma/at_xdmac.c
> 
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index 9b1ea0e..042ebb1 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -107,6 +107,13 @@ config AT_HDMAC
>  	help
>  	  Support the Atmel AHB DMA controller.
>  
> +config AT_XDMAC
> +	tristate "Atmel XDMA support"
> +	depends on (ARCH_AT91 || COMPILE_TEST)
> +	select DMA_ENGINE
> +	help
> +	  Support the Atmel XDMA controller.
> +
>  config FSL_DMA
>  	tristate "Freescale Elo series DMA support"
>  	depends on FSL_SOC
> diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
> index c6adb92..f32bfe1 100644
> --- a/drivers/dma/Makefile
> +++ b/drivers/dma/Makefile
> @@ -17,6 +17,7 @@ obj-$(CONFIG_PPC_BESTCOMM) += bestcomm/
>  obj-$(CONFIG_MV_XOR) += mv_xor.o
>  obj-$(CONFIG_DW_DMAC_CORE) += dw/
>  obj-$(CONFIG_AT_HDMAC) += at_hdmac.o
> +obj-$(CONFIG_AT_XDMAC) += at_xdmac.o
>  obj-$(CONFIG_MX3_IPU) += ipu/
>  obj-$(CONFIG_TXX9_DMAC) += txx9dmac.o
>  obj-$(CONFIG_SH_DMAE_BASE) += sh/
> diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
> new file mode 100644
> index 0000000..b05e259
> --- /dev/null
> +++ b/drivers/dma/at_xdmac.c
> @@ -0,0 +1,1491 @@
> +/*
> + * Driver for the Atmel Extensible DMA Controller (aka XDMAC on AT91 systems)
> + *
> + * Copyright (C) 2014 Atmel Corporation
> + *
> + * Author: Ludovic Desroches <[e-mail]>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published by
> + * the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <asm/barrier.h>
> +#include <dt-bindings/dma/at91.h>
> +#include <linux/clk.h>
> +#include <linux/dmaengine.h>
> +#include <linux/dmapool.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/list.h>
> +#include <linux/module.h>
> +#include <linux/of_dma.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm.h>
> +
> +#include "dmaengine.h"
> +
> +/* Global registers */
> +#define AT_XDMAC_GTYPE		0x00	/* Global Type Register */
> +#define		AT_XDMAC_NB_CH(i)	(((i) & 0x1F) + 1)		/* Number of Channels Minus One */
> +#define		AT_XDMAC_FIFO_SZ(i)	(((i) >> 5) & 0x7FF)		/* Number of Bytes */
> +#define		AT_XDMAC_NB_REQ(i)	((((i) >> 16) & 0x3F) + 1)	/* Number of Peripheral Requests Minus One */
> +#define AT_XDMAC_GCFG		0x04	/* Global Configuration Register */
> +#define AT_XDMAC_GWAC		0x08	/* Global Weighted Arbiter Configuration Register */
> +#define AT_XDMAC_GIE		0x0C	/* Global Interrupt Enable Register */
> +#define AT_XDMAC_GID		0x10	/* Global Interrupt Disable Register */
> +#define AT_XDMAC_GIM		0x14	/* Global Interrupt Mask Register */
> +#define AT_XDMAC_GIS		0x18	/* Global Interrupt Status Register */
> +#define AT_XDMAC_GE		0x1C	/* Global Channel Enable Register */
> +#define AT_XDMAC_GD		0x20	/* Global Channel Disable Register */
> +#define AT_XDMAC_GS		0x24	/* Global Channel Status Register */
> +#define AT_XDMAC_GRS		0x28	/* Global Channel Read Suspend Register */
> +#define AT_XDMAC_GWS		0x2C	/* Global Write Suspend Register */
> +#define AT_XDMAC_GRWS		0x30	/* Global Channel Read Write Suspend Register */
> +#define AT_XDMAC_GRWR		0x34	/* Global Channel Read Write Resume Register */
> +#define AT_XDMAC_GSWR		0x38	/* Global Channel Software Request Register */
> +#define AT_XDMAC_GSWS		0x3C	/* Global channel Software Request Status Register */
> +#define AT_XDMAC_GSWF		0x40	/* Global Channel Software Flush Request Register */
> +#define AT_XDMAC_VERSION	0xFFC	/* XDMAC Version Register */
> +
> +/* Channel relative registers offsets */
> +#define AT_XDMAC_CIE		0x00	/* Channel Interrupt Enable Register */
> +#define		AT_XDMAC_CIE_BIE	BIT(0)	/* End of Block Interrupt Enable Bit */
> +#define		AT_XDMAC_CIE_LIE	BIT(1)	/* End of Linked List Interrupt Enable Bit */
> +#define		AT_XDMAC_CIE_DIE	BIT(2)	/* End of Disable Interrupt Enable Bit */
> +#define		AT_XDMAC_CIE_FIE	BIT(3)	/* End of Flush Interrupt Enable Bit */
> +#define		AT_XDMAC_CIE_RBEIE	BIT(4)	/* Read Bus Error Interrupt Enable Bit */
> +#define		AT_XDMAC_CIE_WBEIE	BIT(5)	/* Write Bus Error Interrupt Enable Bit */
> +#define		AT_XDMAC_CIE_ROIE	BIT(6)	/* Request Overflow Interrupt Enable Bit */
> +#define AT_XDMAC_CID		0x04	/* Channel Interrupt Disable Register */
> +#define		AT_XDMAC_CID_BID	BIT(0)	/* End of Block Interrupt Disable Bit */
> +#define		AT_XDMAC_CID_LID	BIT(1)	/* End of Linked List Interrupt Disable Bit */
> +#define		AT_XDMAC_CID_DID	BIT(2)	/* End of Disable Interrupt Disable Bit */
> +#define		AT_XDMAC_CID_FID	BIT(3)	/* End of Flush Interrupt Disable Bit */
> +#define		AT_XDMAC_CID_RBEID	BIT(4)	/* Read Bus Error Interrupt Disable Bit */
> +#define		AT_XDMAC_CID_WBEID	BIT(5)	/* Write Bus Error Interrupt Disable Bit */
> +#define		AT_XDMAC_CID_ROID	BIT(6)	/* Request Overflow Interrupt Disable Bit */
> +#define AT_XDMAC_CIM		0x08	/* Channel Interrupt Mask Register */
> +#define		AT_XDMAC_CIM_BIM	BIT(0)	/* End of Block Interrupt Mask Bit */
> +#define		AT_XDMAC_CIM_LIM	BIT(1)	/* End of Linked List Interrupt Mask Bit */
> +#define		AT_XDMAC_CIM_DIM	BIT(2)	/* End of Disable Interrupt Mask Bit */
> +#define		AT_XDMAC_CIM_FIM	BIT(3)	/* End of Flush Interrupt Mask Bit */
> +#define		AT_XDMAC_CIM_RBEIM	BIT(4)	/* Read Bus Error Interrupt Mask Bit */
> +#define		AT_XDMAC_CIM_WBEIM	BIT(5)	/* Write Bus Error Interrupt Mask Bit */
> +#define		AT_XDMAC_CIM_ROIM	BIT(6)	/* Request Overflow Interrupt Mask Bit */
> +#define AT_XDMAC_CIS		0x0C	/* Channel Interrupt Status Register */
> +#define		AT_XDMAC_CIS_BIS	BIT(0)	/* End of Block Interrupt Status Bit */
> +#define		AT_XDMAC_CIS_LIS	BIT(1)	/* End of Linked List Interrupt Status Bit */
> +#define		AT_XDMAC_CIS_DIS	BIT(2)	/* End of Disable Interrupt Status Bit */
> +#define		AT_XDMAC_CIS_FIS	BIT(3)	/* End of Flush Interrupt Status Bit */
> +#define		AT_XDMAC_CIS_RBEIS	BIT(4)	/* Read Bus Error Interrupt Status Bit */
> +#define		AT_XDMAC_CIS_WBEIS	BIT(5)	/* Write Bus Error Interrupt Status Bit */
> +#define		AT_XDMAC_CIS_ROIS	BIT(6)	/* Request Overflow Interrupt Status Bit */
> +#define AT_XDMAC_CSA		0x10	/* Channel Source Address Register */
> +#define AT_XDMAC_CDA		0x14	/* Channel Destination Address Register */
> +#define AT_XDMAC_CNDA		0x18	/* Channel Next Descriptor Address Register */
> +#define 	AT_XDMAC_CNDA_NDAIF(i)	((i) & 0x1)			/* Channel x Next Descriptor Interface */
> +#define		AT_XDMAC_CNDA_NDA(i)	((i) & 0xfffffffc)		/* Channel x Next Descriptor Address */
> +#define AT_XDMAC_CNDC		0x1C	/* Channel Next Descriptor Control Register */
> +#define		AT_XDMAC_CNDC_NDE		(0x1 << 0)		/* Channel x Next Descriptor Enable */
> +#define		AT_XDMAC_CNDC_NDSUP		(0x1 << 1)		/* Channel x Next Descriptor Source Update */
> +#define		AT_XDMAC_CNDC_NDDUP		(0x1 << 2)		/* Channel x Next Descriptor Destination Update */
> +#define		AT_XDMAC_CNDC_NDVIEW_NDV0	(0x0 << 3)		/* Channel x Next Descriptor View 0 */
> +#define		AT_XDMAC_CNDC_NDVIEW_NDV1	(0x1 << 3)		/* Channel x Next Descriptor View 1 */
> +#define		AT_XDMAC_CNDC_NDVIEW_NDV2	(0x2 << 3)		/* Channel x Next Descriptor View 2 */
> +#define		AT_XDMAC_CNDC_NDVIEW_NDV3	(0x3 << 3)		/* Channel x Next Descriptor View 3 */
> +#define AT_XDMAC_CUBC		0x20	/* Channel Microblock Control Register */
> +#define AT_XDMAC_CBC		0x24	/* Channel Block Control Register */
> +#define AT_XDMAC_CC		0x28	/* Channel Configuration Register */
> +#define		AT_XDMAC_CC_TYPE	(0x1 << 0)	/* Channel Transfer Type */
> +#define			AT_XDMAC_CC_TYPE_MEM_TRAN	(0x0 << 0)	/* Memory to Memory Transfer */
> +#define			AT_XDMAC_CC_TYPE_PER_TRAN	(0x1 << 0)	/* Peripheral to Memory or Memory to Peripheral Transfer */
> +#define		AT_XDMAC_CC_MBSIZE_MASK	(0x3 << 1)
> +#define			AT_XDMAC_CC_MBSIZE_SINGLE	(0x0 << 1)
> +#define			AT_XDMAC_CC_MBSIZE_FOUR		(0x1 << 1)
> +#define			AT_XDMAC_CC_MBSIZE_EIGHT	(0x2 << 1)
> +#define			AT_XDMAC_CC_MBSIZE_SIXTEEN	(0x3 << 1)
> +#define		AT_XDMAC_CC_DSYNC	(0x1 << 4)	/* Channel Synchronization */
> +#define			AT_XDMAC_CC_DSYNC_PER2MEM	(0x0 << 4)
> +#define			AT_XDMAC_CC_DSYNC_MEM2PER	(0x1 << 4)
> +#define		AT_XDMAC_CC_PROT	(0x1 << 5)	/* Channel Protection */
> +#define			AT_XDMAC_CC_PROT_SEC		(0x0 << 5)
> +#define			AT_XDMAC_CC_PROT_UNSEC		(0x1 << 5)
> +#define		AT_XDMAC_CC_SWREQ	(0x1 << 6)	/* Channel Software Request Trigger */
> +#define			AT_XDMAC_CC_SWREQ_HWR_CONNECTED	(0x0 << 6)
> +#define			AT_XDMAC_CC_SWREQ_SWR_CONNECTED	(0x1 << 6)
> +#define		AT_XDMAC_CC_MEMSET	(0x1 << 7)	/* Channel Fill Block of memory */
> +#define			AT_XDMAC_CC_MEMSET_NORMAL_MODE	(0x0 << 7)
> +#define			AT_XDMAC_CC_MEMSET_HW_MODE	(0x1 << 7)
> +#define		AT_XDMAC_CC_CSIZE_MASK	(0x7 << 8)	/* Channel Chunk Size */
> +#define			AT_XDMAC_CC_CSIZE_CHK_1		(0x0 << 8)
> +#define			AT_XDMAC_CC_CSIZE_CHK_2		(0x1 << 8)
> +#define			AT_XDMAC_CC_CSIZE_CHK_4		(0x2 << 8)
> +#define			AT_XDMAC_CC_CSIZE_CHK_8		(0x3 << 8)
> +#define			AT_XDMAC_CC_CSIZE_CHK_16	(0x4 << 8)
> +#define		AT_XDMAC_CC_DWIDTH(i)	((i) << 11)	/* Channel Data Width */
> +#define			AT_XDMAC_CC_DWIDTH_BYTE		0x0
> +#define			AT_XDMAC_CC_DWIDTH_HALFWORD	0x1
> +#define			AT_XDMAC_CC_DWIDTH_WORD		0x2
> +#define			AT_XDMAC_CC_DWIDTH_DWORD	0x3
> +#define		AT_XDMAC_CC_SIF(i)	((0x1 & (i)) << 13)	/* Channel Source Interface Identifier */
> +#define		AT_XDMAC_CC_DIF(i)	((0x1 & (i)) << 14)	/* Channel Destination Interface Identifier */
> +#define		AT_XDMAC_CC_SAM_MASK	(0x3 << 16)	/* Channel Source Addressing Mode */
> +#define			AT_XDMAC_CC_SAM_FIXED_AM	(0x0 << 16)
> +#define			AT_XDMAC_CC_SAM_INCREMENTED_AM	(0x1 << 16)
> +#define			AT_XDMAC_CC_SAM_UBS_AM		(0x2 << 16)
> +#define			AT_XDMAC_CC_SAM_UBS_DS_AM	(0x3 << 16)
> +#define		AT_XDMAC_CC_DAM_MASK	(0x3 << 18)	/* Channel Source Addressing Mode */
> +#define			AT_XDMAC_CC_DAM_FIXED_AM	(0x0 << 18)
> +#define			AT_XDMAC_CC_DAM_INCREMENTED_AM	(0x1 << 18)
> +#define			AT_XDMAC_CC_DAM_UBS_AM		(0x2 << 18)
> +#define			AT_XDMAC_CC_DAM_UBS_DS_AM	(0x3 << 18)
> +#define		AT_XDMAC_CC_INITD	(0x1 << 21)	/* Channel Initialization Terminated (read only) */
> +#define			AT_XDMAC_CC_INITD_TERMINATED	(0x0 << 21)
> +#define			AT_XDMAC_CC_INITD_IN_PROGRESS	(0x1 << 21)
> +#define		AT_XDMAC_CC_RDIP	(0x1 << 22)	/* Read in Progress (read only) */
> +#define			AT_XDMAC_CC_RDIP_DONE		(0x0 << 22)
> +#define			AT_XDMAC_CC_RDIP_IN_PROGRESS	(0x1 << 22)
> +#define		AT_XDMAC_CC_WRIP	(0x1 << 23)	/* Write in Progress (read only) */
> +#define			AT_XDMAC_CC_WRIP_DONE		(0x0 << 23)
> +#define			AT_XDMAC_CC_WRIP_IN_PROGRESS	(0x1 << 23)
> +#define		AT_XDMAC_CC_PERID(i)	(0x7f & (h) << 24)	/* Channel Peripheral Identifier */
> +#define AT_XDMAC_CDS_MSP	0x2C	/* Channel Data Stride Memory Set Pattern */
> +#define AT_XDMAC_CSUS		0x30	/* Channel Source Microblock Stride */
> +#define AT_XDMAC_CDUS		0x34	/* Channel Destination Microblock Stride */
> +
> +#define AT_XDMAC_CHAN_REG_BASE	0x50	/* Channel registers base address */
> +
> +/* Microblock control members */
> +#define AT_XDMAC_MBR_UBC_UBLEN_MAX	0xFFFFFFUL	/* Maximum Microblock Length */
> +#define AT_XDMAC_MBR_UBC_NDE		(0x1 << 24)	/* Next Descriptor Enable */
> +#define AT_XDMAC_MBR_UBC_NSEN		(0x1 << 25)	/* Next Descriptor Source Update */
> +#define AT_XDMAC_MBR_UBC_NDEN		(0x1 << 26)	/* Next Descriptor Destination Update */
> +#define AT_XDMAC_MBR_UBC_NDV0		(0x0 << 27)	/* Next Descriptor View 0 */
> +#define AT_XDMAC_MBR_UBC_NDV1		(0x1 << 27)	/* Next Descriptor View 1 */
> +#define AT_XDMAC_MBR_UBC_NDV2		(0x2 << 27)	/* Next Descriptor View 2 */
> +#define AT_XDMAC_MBR_UBC_NDV3		(0x3 << 27)	/* Next Descriptor View 3 */
> +
> +#define AT_XDMAC_MAX_CHAN	0x20
> +
> +enum atc_status {
> +	AT_XDMAC_CHAN_IS_CYCLIC = 0,
> +	AT_XDMAC_CHAN_IS_PAUSED,
> +};
> +
> +/* ----- Channels ----- */
> +struct at_xdmac_chan {
> +	struct dma_chan		chan;
> +	void __iomem		*ch_regs;
> +	u32			mask;		/* Channel Mask */
> +	u32			cfg;		/* Channel Configuration Register */
> +	u8			perid;		/* Peripheral ID */
> +	u8			dwidth;		/* Data Width */
> +	u8			perif;		/* Peripheral Interface */
> +	u8			memif;		/* Memory Interface */
> +	u32			save_cim;
> +	u32			save_cnda;
> +	u32			save_cndc;
> +	unsigned long		status;
> +	struct tasklet_struct	tasklet;
> +	struct dma_slave_config	dma_sconfig;
> +
> +	spinlock_t		lock;
> +
> +	struct list_head	xfers_list;
> +	struct list_head	free_descs_list;
> +};
> +
> +
> +/* ----- Controller ----- */
> +struct at_xdmac {
> +	struct dma_device	dma;
> +	void __iomem		*regs;
> +	int			irq;
> +	struct clk		*clk;
> +	u32			save_gim;
> +	u32			save_gs;
> +	struct dma_pool		*at_xdmac_desc_pool;
> +	struct at_xdmac_chan	chan[0];
> +};
> +
> +
> +/* ----- Descriptors ----- */
> +
> +/* Linked List Descriptor */
> +struct at_xdmac_lld {
> +	dma_addr_t	mbr_nda;	/* Next Descriptor Member */
> +	u32		mbr_ubc;	/* Microblock Control Member */
> +	dma_addr_t	mbr_sa;		/* Source Address Member */
> +	dma_addr_t	mbr_da;		/* Destination Address Member */
> +	u32		mbr_cfg;	/* Configuration Register */
> +};
> +
> +
> +struct at_xdmac_desc {
> +	struct at_xdmac_lld		lld;
> +	enum dma_transfer_direction	direction;
> +	struct dma_async_tx_descriptor	tx_dma_desc;
> +	struct list_head		desc_node;
> +	/* Following members are only used by the first descriptor */
> +	bool				active_xfer;
> +	unsigned int			xfer_size;
> +	struct list_head		descs_list;
> +	struct list_head		xfer_node;
> +};
> +
> +static inline void __iomem *at_xdmac_chan_reg_base(struct at_xdmac *atxdmac, unsigned int chan_nb)
> +{
> +	return atxdmac->regs + (AT_XDMAC_CHAN_REG_BASE + chan_nb * 0x40);
> +}
> +
> +#define at_xdmac_read(atxdmac, reg) readl_relaxed((atxdmac)->regs + (reg))
> +#define at_xdmac_write(atxdmac, reg, value) \
> +	writel_relaxed((value), (atxdmac)->regs + (reg))
> +
> +#define at_xdmac_chan_read(atchan, reg) readl_relaxed((atchan)->ch_regs + (reg))
> +#define at_xdmac_chan_write(atchan, reg, value) writel_relaxed((value), (atchan)->ch_regs + (reg))
> +
> +static inline struct at_xdmac_chan *to_at_xdmac_chan(struct dma_chan *dchan)
> +{
> +	return container_of(dchan, struct at_xdmac_chan, chan);
> +}
> +
> +static struct device *chan2dev(struct dma_chan *chan)
> +{
> +	return &chan->dev->device;
> +}
> +
> +static inline struct at_xdmac *to_at_xdmac(struct dma_device *ddev)
> +{
> +	return container_of(ddev, struct at_xdmac, dma);
> +}
> +
> +static inline struct at_xdmac_desc *txd_to_at_desc(struct dma_async_tx_descriptor *txd)
> +{
> +	return container_of(txd, struct at_xdmac_desc, tx_dma_desc);
> +}
> +
> +static inline int at_xdmac_chan_is_cyclic(struct at_xdmac_chan *atchan)
> +{
> +	return test_bit(AT_XDMAC_CHAN_IS_CYCLIC, &atchan->status);
> +}
> +
> +static inline int at_xdmac_chan_is_paused(struct at_xdmac_chan *atchan)
> +{
> +	return test_bit(AT_XDMAC_CHAN_IS_PAUSED, &atchan->status);
> +}
> +
> +static inline u32 at_xdmac_csize(u32 maxburst)
> +{
> +	u32 csize;
> +
> +	switch (ffs(maxburst) - 1) {
> +	case 1:
> +		csize = AT_XDMAC_CC_CSIZE_CHK_2;
> +		break;
> +	case 2:
> +		csize = AT_XDMAC_CC_CSIZE_CHK_4;
> +		break;
> +	case 3:
> +		csize = AT_XDMAC_CC_CSIZE_CHK_8;
> +		break;
> +	case 4:
> +		csize = AT_XDMAC_CC_CSIZE_CHK_16;
> +		break;
> +	default:
> +		csize = AT_XDMAC_CC_CSIZE_CHK_1;
> +	}
> +
> +	return csize;
> +};
> +
> +static unsigned int init_nr_desc_per_channel = 64;
> +module_param(init_nr_desc_per_channel, uint, 0644);
> +MODULE_PARM_DESC(init_nr_desc_per_channel,
> +		 "initial descriptors per channel (default: 64)");
> +
> +
> +static bool at_xdmac_chan_is_enabled(struct at_xdmac_chan *atchan)
> +{
> +	return at_xdmac_chan_read(atchan, AT_XDMAC_GS) & atchan->mask;
> +}
> +
> +static void at_xdmac_off(struct at_xdmac *atxdmac)
> +{
> +	at_xdmac_write(atxdmac, AT_XDMAC_GD, -1L);
> +
> +	/* Wait that all chans are disabled. */
> +	while (at_xdmac_read(atxdmac, AT_XDMAC_GS))
> +		cpu_relax();
> +
> +	at_xdmac_write(atxdmac, AT_XDMAC_GID, -1L);
> +}
> +
> +/* Call with lock hold. */
> +static void at_xdmac_start_xfer(struct at_xdmac_chan *atchan,
> +				struct at_xdmac_desc *first)
> +{
> +	struct at_xdmac	*atxdmac = to_at_xdmac(atchan->chan.device);
> +	u32		reg;
> +
> +	dev_vdbg(chan2dev(&atchan->chan), "%s: desc 0x%p\n", __func__, first);
> +
> +	if (at_xdmac_chan_is_enabled(atchan))
> +		return;
> +
> +	/* Set transfer as active to not try to start it again. */
> +	first->active_xfer = true;
> +
> +	/* Tell xdmac where to get the first descriptor. */
> +	reg = AT_XDMAC_CNDA_NDA(first->tx_dma_desc.phys)
> +	      | AT_XDMAC_CNDA_NDAIF(atchan->memif);
> +	at_xdmac_chan_write(atchan, AT_XDMAC_CNDA, reg);
> +
> +	/*
> +	 * When doing memory to memory transfer we need to use the next
> +	 * descriptor view 2 since some fields of the configuration register
> +	 * depend on transfer size and src/dest addresses.
> +	 */
> +	if (atchan->cfg & AT_XDMAC_CC_TYPE_PER_TRAN) {
> +		reg = AT_XDMAC_CNDC_NDVIEW_NDV1;
> +		at_xdmac_chan_write(atchan, AT_XDMAC_CC, atchan->cfg);
> +	} else {
> +		reg = AT_XDMAC_CNDC_NDVIEW_NDV2;
> +	}
> +
> +	reg |= AT_XDMAC_CNDC_NDDUP
> +	       | AT_XDMAC_CNDC_NDSUP
> +	       | AT_XDMAC_CNDC_NDE;
> +	at_xdmac_chan_write(atchan, AT_XDMAC_CNDC, reg);
> +
> +	dev_vdbg(chan2dev(&atchan->chan),
> +		 "%s: XDMAC_CC=0x%08x XDMAC_CNDA=0x%08x, XDMAC_CNDC=0x%08x, "
> +		 "XDMAC_CSA=0x%08x, XDMAC_CDA=0x%08x, XDMAC_CUBC=0x%08x\n",
> +		 __func__, at_xdmac_chan_read(atchan, AT_XDMAC_CC),
> +		 at_xdmac_chan_read(atchan, AT_XDMAC_CNDA),
> +		 at_xdmac_chan_read(atchan, AT_XDMAC_CNDC),
> +		 at_xdmac_chan_read(atchan, AT_XDMAC_CSA),
> +		 at_xdmac_chan_read(atchan, AT_XDMAC_CDA),
> +		 at_xdmac_chan_read(atchan, AT_XDMAC_CUBC));
> +
> +	/*
> +	 * There is no end of list when doing cyclic dma, we need to get
> +	 * an interrupt after each periods.
> +	 */
> +	if (at_xdmac_chan_is_cyclic(atchan))
> +		at_xdmac_chan_write(atchan, AT_XDMAC_CIE, AT_XDMAC_CIE_BIE);
> +	else
> +		at_xdmac_chan_write(atchan, AT_XDMAC_CIE, AT_XDMAC_CIE_LIE);
> +	at_xdmac_write(atxdmac, AT_XDMAC_GIE, atchan->mask);
> +	dev_vdbg(chan2dev(&atchan->chan),
> +		 "%s: enable channel (0x%08x)\n", __func__, atchan->mask);
> +	wmb();
> +	at_xdmac_write(atxdmac, AT_XDMAC_GE, atchan->mask);
> +
> +	dev_vdbg(chan2dev(&atchan->chan),
> +		 "%s: XDMAC_CC=0x%08x XDMAC_CNDA=0x%08x, XDMAC_CNDC=0x%08x, "
> +		 "XDMAC_CSA=0x%08x, XDMAC_CDA=0x%08x, XDMAC_CUBC=0x%08x\n",
> +		 __func__, at_xdmac_chan_read(atchan, AT_XDMAC_CC),
> +		 at_xdmac_chan_read(atchan, AT_XDMAC_CNDA),
> +		 at_xdmac_chan_read(atchan, AT_XDMAC_CNDC),
> +		 at_xdmac_chan_read(atchan, AT_XDMAC_CSA),
> +		 at_xdmac_chan_read(atchan, AT_XDMAC_CDA),
> +		 at_xdmac_chan_read(atchan, AT_XDMAC_CUBC));
> +
> +}
> +
> +static dma_cookie_t at_xdmac_tx_submit(struct dma_async_tx_descriptor *tx)
> +{
> +	struct at_xdmac_desc	*desc = txd_to_at_desc(tx);
> +	struct at_xdmac_chan	*atchan = to_at_xdmac_chan(tx->chan);
> +	dma_cookie_t		cookie;
> +	unsigned long		flags;
> +
> +	spin_lock_irqsave(&atchan->lock, flags);
> +	cookie = dma_cookie_assign(tx);
> +
> +	dev_vdbg(chan2dev(tx->chan), "%s: atchan 0x%p, add desc 0x%p to xfers_list\n",
> +		 __func__, atchan, desc);
> +	list_add_tail(&desc->xfer_node, &atchan->xfers_list);
> +	if (list_is_singular(&atchan->xfers_list))
> +		at_xdmac_start_xfer(atchan, desc);
> +
> +	spin_unlock_irqrestore(&atchan->lock, flags);
> +	return cookie;
> +}
> +
> +static struct at_xdmac_desc *at_xdmac_alloc_desc(struct dma_chan *chan,
> +						 gfp_t gfp_flags)
> +{
> +	struct at_xdmac_desc	*desc;
> +	struct at_xdmac		*atxdmac = to_at_xdmac(chan->device);
> +	dma_addr_t		phys;
> +
> +	desc = dma_pool_alloc(atxdmac->at_xdmac_desc_pool, gfp_flags, &phys);
> +	if (desc) {
> +		memset(desc, 0, sizeof(*desc));
> +		INIT_LIST_HEAD(&desc->descs_list);
> +		dma_async_tx_descriptor_init(&desc->tx_dma_desc, chan);
> +		desc->tx_dma_desc.tx_submit = at_xdmac_tx_submit;
> +		desc->tx_dma_desc.phys = phys;
> +	}
> +
> +	return desc;
> +}
> +
> +/* Call must be protected by lock. */
> +static struct at_xdmac_desc *at_xdmac_get_desc(struct at_xdmac_chan *atchan)
> +{
> +	struct at_xdmac_desc *desc;
> +
> +	if (list_empty(&atchan->free_descs_list)) {
> +		desc = at_xdmac_alloc_desc(&atchan->chan, GFP_NOWAIT);
> +	} else {
> +		desc = list_first_entry(&atchan->free_descs_list,
> +					struct at_xdmac_desc, desc_node);
> +		list_del(&desc->desc_node);
> +		desc->active_xfer = false;
> +	}
> +
> +	return desc;
> +}
> +
> +static struct dma_chan *at_xdmac_xlate(struct of_phandle_args *dma_spec,
> +				       struct of_dma *of_dma)
> +{
> +	struct at_xdmac		*atxdmac = of_dma->of_dma_data;
> +	struct at_xdmac_chan	*atchan;
> +	struct dma_chan		*chan;
> +	struct device		*dev = atxdmac->dma.dev;
> +
> +	if (dma_spec->args_count != 2) {
> +		dev_err(dev, "dma phandler args: bad number of args\n");
> +		return NULL;
> +	}
> +
> +	chan = dma_get_any_slave_channel(&atxdmac->dma);
> +	if (!chan) {
> +		dev_err(dev, "can't get a dma channel\n");
> +		return NULL;
> +	}
> +
> +	atchan = to_at_xdmac_chan(chan);
> +	atchan->memif = AT91_XDMAC_DT_GET_MEM_IF(dma_spec->args[0]);
> +	atchan->perif = AT91_XDMAC_DT_GET_PER_IF(dma_spec->args[0]);
> +	atchan->perid = AT91_XDMAC_DT_GET_PERID(dma_spec->args[1]);
> +	dev_dbg(dev, "chan dt cfg: memif=%u perif=%u perid=%u\n",
> +		 atchan->memif, atchan->perif, atchan->perid);
> +
> +	return chan;
> +}
> +
> +static int at_xdmac_set_slave_config(struct dma_chan *chan,
> +				      struct dma_slave_config *sconfig)
> +{
> +	struct at_xdmac_chan 	*atchan = to_at_xdmac_chan(chan);
> +
> +	atchan->cfg = AT91_XDMAC_DT_PERID(atchan->perid)
> +		      |	AT_XDMAC_CC_SWREQ_HWR_CONNECTED
> +		      | AT_XDMAC_CC_MBSIZE_SIXTEEN
> +		      | AT_XDMAC_CC_TYPE_PER_TRAN;
> +
> +	if (sconfig->direction == DMA_DEV_TO_MEM) {
> +		atchan->cfg |= AT_XDMAC_CC_DAM_INCREMENTED_AM
> +			       | AT_XDMAC_CC_SAM_FIXED_AM
> +			       | AT_XDMAC_CC_DIF(atchan->memif)
> +			       | AT_XDMAC_CC_SIF(atchan->perif)
> +			       | AT_XDMAC_CC_DSYNC_PER2MEM;
> +		atchan->dwidth = ffs(sconfig->src_addr_width) - 1;
> +		atchan->cfg |= AT_XDMAC_CC_DWIDTH(atchan->dwidth);
> +		atchan->cfg |= at_xdmac_csize(sconfig->src_maxburst);
> +	} else if (sconfig->direction == DMA_MEM_TO_DEV) {
> +		atchan->cfg |= AT_XDMAC_CC_DAM_FIXED_AM
> +			       | AT_XDMAC_CC_SAM_INCREMENTED_AM
> +			       | AT_XDMAC_CC_DIF(atchan->perif)
> +			       | AT_XDMAC_CC_SIF(atchan->memif)
> +			       | AT_XDMAC_CC_DSYNC_MEM2PER;
> +		atchan->dwidth = ffs(sconfig->dst_addr_width) - 1;
> +		atchan->cfg |= AT_XDMAC_CC_DWIDTH(atchan->dwidth);
> +		atchan->cfg |= at_xdmac_csize(sconfig->dst_maxburst);
> +	} else {
> +		return -EINVAL;
> +	}
> +
> +	/*
> +	 * Src address and dest addr are needed to configure the link list
> +	 * descriptor so keep the slave configuration.
> +	 */
> +	memcpy(&atchan->dma_sconfig, sconfig, sizeof(struct dma_slave_config));
> +
> +	dev_dbg(chan2dev(chan), "%s: atchan->cfg=0x%08x\n", __func__, atchan->cfg);
> +
> +	return 0;
> +}
> +
> +static struct dma_async_tx_descriptor *
> +at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
> +		       unsigned int sg_len, enum dma_transfer_direction direction,
> +		       unsigned long flags, void *context)
> +{
> +	struct at_xdmac_chan 	*atchan = to_at_xdmac_chan(chan);
> +	struct dma_slave_config	*sconfig = &atchan->dma_sconfig;
> +	struct at_xdmac_desc	*first = NULL, *prev = NULL;
> +	struct scatterlist	*sg;
> +	int 			i;
> +
> +	if (!sgl)
> +		return NULL;
> +
> +	if (!is_slave_direction(direction)) {
> +		dev_err(chan2dev(chan), "invalid DMA direction\n");
> +		return NULL;
> +	}
> +
> +	dev_dbg(chan2dev(chan), "%s: sg_len=%d, dir=%s, flags=0x%lx\n",
> +		 __func__, sg_len,
> +		 direction == DMA_MEM_TO_DEV ? "to device" : "from device",
> +		 flags);
> +
> +	/* Protect dma_sconfig field that can be modified by set_slave_conf. */
> +	spin_lock(&atchan->lock);
> +
> +	/* Prepare descriptors. */
> +	for_each_sg(sgl, sg, sg_len, i) {
> +		struct at_xdmac_desc	*desc = NULL;
> +		u32			len, mem;
> +
> +		len = sg_dma_len(sg);
> +		mem = sg_dma_address(sg);
> +		if (unlikely(!len)) {
> +			dev_err(chan2dev(chan), "sg data length is zero\n");
> +			spin_unlock(&atchan->lock);
> +			return NULL;
> +		}
> +		dev_dbg(chan2dev(chan), "%s: * sg%d len=%u, mem=0x%08x\n",
> +			 __func__, i, len, mem);
> +
> +		desc = at_xdmac_get_desc(atchan);
> +		if (!desc) {
> +			dev_err(chan2dev(chan), "can't get descriptor\n");
> +			if (first)
> +				list_splice_init(&first->descs_list, &atchan->free_descs_list);
> +			spin_unlock(&atchan->lock);
> +			return NULL;
> +		}
> +
> +		/* Linked list descriptor setup. */
> +		if (direction == DMA_DEV_TO_MEM) {
> +			desc->lld.mbr_sa = sconfig->src_addr;
> +			desc->lld.mbr_da = mem;
> +		} else {
> +			desc->lld.mbr_sa = mem;
> +			desc->lld.mbr_da = sconfig->dst_addr;
> +		}
> +		desc->lld.mbr_ubc = AT_XDMAC_MBR_UBC_NDV1		/* next descriptor view */
> +			| AT_XDMAC_MBR_UBC_NDEN				/* next descriptor dst parameter update */
> +			| AT_XDMAC_MBR_UBC_NSEN				/* next descriptor src parameter update */
> +			| (i == sg_len - 1 ? 0 : AT_XDMAC_MBR_UBC_NDE)	/* descriptor fetch */
> +			| len / (1 << atchan->dwidth);			/* microblock length */
> +		dev_dbg(chan2dev(chan),
> +			 "%s: lld: mbr_sa=0x%08x, mbr_da=0x%08x, mbr_ubc=0x%08x\n",
> +			 __func__, desc->lld.mbr_sa, desc->lld.mbr_da, desc->lld.mbr_ubc);
> +
> +		/* Chain lld. */
> +		if (prev) {
> +			prev->lld.mbr_nda = desc->tx_dma_desc.phys;
> +			dev_dbg(chan2dev(chan),
> +				 "%s: chain lld: prev=0x%p, mbr_nda=0x%08x\n",
> +				 __func__, prev, prev->lld.mbr_nda);
> +		}
> +
> +		prev = desc;
> +		if (!first)
> +			first = desc;
> +
> +		dev_dbg(chan2dev(chan), "%s: add desc 0x%p to descs_list 0x%p\n",
> +			 __func__, desc, first);
> +		list_add_tail(&desc->desc_node, &first->descs_list);
> +	}
> +
> +	spin_unlock(&atchan->lock);
> +
> +	first->tx_dma_desc.cookie = -EBUSY;
> +	first->tx_dma_desc.flags = flags;
> +	first->xfer_size = sg_len;
> +
> +	return &first->tx_dma_desc;
> +}
> +
> +static struct dma_async_tx_descriptor *
> +at_xdmac_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t buf_addr,
> +			 size_t buf_len, size_t period_len,
> +			 enum dma_transfer_direction direction,
> +			 unsigned long flags)
> +{
> +	struct at_xdmac_chan 	*atchan = to_at_xdmac_chan(chan);
> +	struct dma_slave_config	*sconfig = &atchan->dma_sconfig;
> +	struct at_xdmac_desc	*first = NULL, *prev = NULL;
> +	unsigned int		periods = buf_len / period_len;
> +	unsigned long		lock_flags;
> +	int 			i;
> +
> +	dev_dbg(chan2dev(chan), "%s: buf_addr=0x%08x, buf_len=%d, period_len=%d, "
> +		"dir=%s, flags=0x%lx\n",
> +		__func__, buf_addr, buf_len, period_len,
> +		direction == DMA_MEM_TO_DEV ? "mem2per" : "per2mem", flags);
> +
> +	if (!is_slave_direction(direction)) {
> +		dev_err(chan2dev(chan), "invalid DMA direction\n");
> +		return NULL;
> +	}
> +
> +	if (test_and_set_bit(AT_XDMAC_CHAN_IS_CYCLIC, &atchan->status)) {
> +		dev_err(chan2dev(chan), "channel currently used\n");
> +		return NULL;
> +	}
> +
> +	for (i = 0; i < periods; i++) {
> +		struct at_xdmac_desc	*desc = NULL;
> +
> +		spin_lock_irqsave(&atchan->lock, lock_flags);
> +		desc = at_xdmac_get_desc(atchan);
> +		spin_unlock_irqrestore(&atchan->lock, lock_flags);
> +		if (!desc) {
> +			dev_err(chan2dev(chan), "can't get descriptor\n");
> +			if (first)
> +				list_splice_init(&first->descs_list, &atchan->free_descs_list);
> +			return NULL;
> +		}
> +		dev_dbg(chan2dev(chan),
> +			"%s: desc=0x%p, tx_dma_desc.phys=0x%08x\n",
> +			__func__, desc, desc->tx_dma_desc.phys);
> +
> +		if (direction == DMA_DEV_TO_MEM) {
> +			desc->lld.mbr_sa = sconfig->src_addr;
> +			desc->lld.mbr_da = buf_addr + i * period_len;
> +		} else {
> +			desc->lld.mbr_sa = buf_addr + i * period_len;
> +			desc->lld.mbr_da = sconfig->dst_addr;
> +		};
> +		desc->lld.mbr_ubc = AT_XDMAC_MBR_UBC_NDV1
> +			| AT_XDMAC_MBR_UBC_NDEN
> +			| AT_XDMAC_MBR_UBC_NSEN
> +			| AT_XDMAC_MBR_UBC_NDE
> +			| period_len >> atchan->dwidth;
> +
> +		dev_dbg(chan2dev(chan),
> +			 "%s: lld: mbr_sa=0x%08x, mbr_da=0x%08x, mbr_ubc=0x%08x\n",
> +			 __func__, desc->lld.mbr_sa, desc->lld.mbr_da, desc->lld.mbr_ubc);
> +
> +		/* Chain lld. */
> +		if (prev) {
> +			prev->lld.mbr_nda = desc->tx_dma_desc.phys;
> +			dev_dbg(chan2dev(chan),
> +				 "%s: chain lld: prev=0x%p, mbr_nda=0x%08x\n",
> +				 __func__, prev, prev->lld.mbr_nda);
> +		}
> +
> +		prev = desc;
> +		if (!first)
> +			first = desc;
> +
> +		dev_dbg(chan2dev(chan), "%s: add desc 0x%p to descs_list 0x%p\n",
> +			 __func__, desc, first);
> +		list_add_tail(&desc->desc_node, &first->descs_list);
> +	}
> +
> +	prev->lld.mbr_nda = first->tx_dma_desc.phys;
> +	dev_dbg(chan2dev(chan),
> +		"%s: chain lld: prev=0x%p, mbr_nda=0x%08x\n",
> +		__func__, prev, prev->lld.mbr_nda);
> +	first->tx_dma_desc.cookie = -EBUSY;
> +	first->tx_dma_desc.flags = flags;
> +	first->xfer_size = buf_len;
> +
> +	return &first->tx_dma_desc;
> +}
> +
> +static struct dma_async_tx_descriptor *
> +at_xdmac_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
> +			 size_t len, unsigned long flags)
> +{
> +	struct at_xdmac_chan 	*atchan = to_at_xdmac_chan(chan);
> +	struct at_xdmac_desc	*first = NULL, *prev = NULL;
> +	size_t			remaining_size = len, xfer_size = 0, ublen;
> +	dma_addr_t		src_addr = src, dst_addr = dest;
> +	u32			dwidth;
> +	/*
> +	 * WARNING: The channel configuration is set here since there is no
> +	 * dmaengine_slave_config call in this case. Moreover we don't know the
> +	 * direction, it involves we can't dynamically set the source and dest
> +	 * interface so we have to use the same one. Only interface 0 allows EBI
> +	 * access. Hopefully we can access DDR through both ports (at least on
> +	 * SAMA5D4x), so we can use the same interface for source and dest,
> +	 * that solves the fact we don't know the direction.
> +	 */
> +	u32			chan_cc = AT_XDMAC_CC_DAM_INCREMENTED_AM
> +					| AT_XDMAC_CC_SAM_INCREMENTED_AM
> +					| AT_XDMAC_CC_DIF(0)
> +					| AT_XDMAC_CC_SIF(0)
> +					| AT_XDMAC_CC_MBSIZE_SIXTEEN
> +					| AT_XDMAC_CC_TYPE_MEM_TRAN;
> +
> +	dev_dbg(chan2dev(chan), "%s: src=0x%08x, dest=0x%08x, len=%d, flags=0x%lx\n",
> +		__func__, src, dest, len, flags);
> +
> +	if (unlikely(!len))
> +		return NULL;
> +
> +	/*
> +	 * Check address alignment to select the greater data width we can use.
> +	 * Some XDMAC implementations don't provide dword transfer, in this
> +	 * case selecting dword has the same behavior as selecting word transfers.
> +	 */
> +	if (!((src_addr | dst_addr) & 7)) {
> +		dwidth = AT_XDMAC_CC_DWIDTH_DWORD;
> +		dev_dbg(chan2dev(chan), "%s: dwidth: double word\n", __func__);
> +	} else if (!((src_addr | dst_addr)  & 3)) {
> +		dwidth = AT_XDMAC_CC_DWIDTH_WORD;
> +		dev_dbg(chan2dev(chan), "%s: dwidth: word\n", __func__);
> +	} else if (!((src_addr | dst_addr) & 1)) {
> +		dwidth = AT_XDMAC_CC_DWIDTH_HALFWORD;
> +		dev_dbg(chan2dev(chan), "%s: dwidth: half word\n", __func__);
> +	} else {
> +		dwidth = AT_XDMAC_CC_DWIDTH_BYTE;
> +		dev_dbg(chan2dev(chan), "%s: dwidth: byte\n", __func__);
> +	}
> +
> +	atchan->cfg = chan_cc | AT_XDMAC_CC_DWIDTH(dwidth);
> +
> +	/* Prepare descriptors. */
> +	while (remaining_size) {
> +		struct at_xdmac_desc	*desc = NULL;
> +
> +		dev_dbg(chan2dev(chan), "%s: remaining_size=%u\n", __func__, remaining_size);
> +
> +		spin_lock_irqsave(&atchan->lock, flags);
> +		desc = at_xdmac_get_desc(atchan);
> +		spin_unlock_irqrestore(&atchan->lock, flags);
> +		if (!desc) {
> +			dev_err(chan2dev(chan), "can't get descriptor\n");
> +			if (first)
> +				list_splice_init(&first->descs_list, &atchan->free_descs_list);
> +			return NULL;
> +		}
> +
> +		/* Update src and dest addresses. */
> +		src_addr += xfer_size;
> +		dst_addr += xfer_size;
> +
> +		if (remaining_size >= AT_XDMAC_MBR_UBC_UBLEN_MAX << dwidth)
> +			xfer_size = AT_XDMAC_MBR_UBC_UBLEN_MAX << dwidth;
> +		else
> +			xfer_size = remaining_size;
> +
> +		dev_dbg(chan2dev(chan), "%s: xfer_size=%u\n", __func__, xfer_size);
> +
> +		/* Check remaining length and change data width if needed. */
> +		if (!((src_addr | dst_addr | xfer_size) & 7)) {
> +			dwidth = AT_XDMAC_CC_DWIDTH_DWORD;
> +			dev_dbg(chan2dev(chan), "%s: dwidth: double word\n", __func__);
> +		} else if (!((src_addr | dst_addr | xfer_size)  & 3)) {
> +			dwidth = AT_XDMAC_CC_DWIDTH_WORD;
> +			dev_dbg(chan2dev(chan), "%s: dwidth: word\n", __func__);
> +		} else if (!((src_addr | dst_addr | xfer_size) & 1)) {
> +			dwidth = AT_XDMAC_CC_DWIDTH_HALFWORD;
> +			dev_dbg(chan2dev(chan), "%s: dwidth: half word\n", __func__);
> +		} else if ((src_addr | dst_addr | xfer_size) & 1) {
> +			dwidth = AT_XDMAC_CC_DWIDTH_BYTE;
> +			dev_dbg(chan2dev(chan), "%s: dwidth: byte\n", __func__);
> +		}
> +		chan_cc |= AT_XDMAC_CC_DWIDTH(dwidth);
> +
> +		ublen = xfer_size >> dwidth;
> +		remaining_size -= xfer_size;
> +
> +		desc->lld.mbr_sa = src_addr;
> +		desc->lld.mbr_da = dst_addr;
> +		desc->lld.mbr_ubc = AT_XDMAC_MBR_UBC_NDV2
> +			| AT_XDMAC_MBR_UBC_NDEN
> +			| AT_XDMAC_MBR_UBC_NSEN
> +			| (remaining_size ? 0 : AT_XDMAC_MBR_UBC_NDE)
> +			| ublen;
> +		desc->lld.mbr_cfg = chan_cc;
> +
> +		dev_dbg(chan2dev(chan),
> +			 "%s: lld: mbr_sa=0x%08x, mbr_da=0x%08x, mbr_ubc=0x%08x, mbr_cfg=0x%08x\n",
> +			 __func__, desc->lld.mbr_sa, desc->lld.mbr_da, desc->lld.mbr_ubc, desc->lld.mbr_cfg);
> +
> +		/* Chain lld. */
> +		if (prev) {
> +			prev->lld.mbr_nda = desc->tx_dma_desc.phys;
> +			dev_dbg(chan2dev(chan),
> +				 "%s: chain lld: prev=0x%p, mbr_nda=0x%08x\n",
> +				 __func__, prev, prev->lld.mbr_nda);
> +		}
> +
> +		prev = desc;
> +		if (!first)
> +			first = desc;
> +
> +		dev_dbg(chan2dev(chan), "%s: add desc 0x%p to descs_list 0x%p\n",
> +			 __func__, desc, first);
> +		list_add_tail(&desc->desc_node, &first->descs_list);
> +	}
> +
> +	first->tx_dma_desc.cookie = -EBUSY;
> +	first->tx_dma_desc.flags = flags;
> +	first->xfer_size = len;
> +
> +	return &first->tx_dma_desc;
> +}
> +
> +static enum dma_status
> +at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
> +		struct dma_tx_state *txstate)
> +{
> +	struct at_xdmac_chan 	*atchan = to_at_xdmac_chan(chan);
> +	struct at_xdmac		*atxdmac = to_at_xdmac(atchan->chan.device);
> +	struct at_xdmac_desc	*desc, *_desc;
> +	struct list_head	*descs_list;
> +	unsigned long		flags;
> +	enum dma_status		ret;
> +	int			residue;
> +	u32			cur_nda;
> +
> +	ret = dma_cookie_status(chan, cookie, txstate);
> +	if (ret == DMA_COMPLETE)
> +		return ret;
> +
> +	if (!txstate)
> +		return ret;
> +
> +	spin_lock_irqsave(&atchan->lock, flags);
> +
> +	desc = list_first_entry(&atchan->xfers_list, struct at_xdmac_desc, xfer_node);
> +
> +	/*
> +	 * If the transfer has not been started yet, don't need to compute the
> +	 * residue, it's the transfer length.
> +	 */
> +	if (!desc->active_xfer) {
> +		dma_set_residue(txstate, desc->xfer_size);
> +		return ret;
> +	}
> +
> +	residue = desc->xfer_size;
> +	/* Flush FIFO. */
> +	at_xdmac_write(atxdmac, AT_XDMAC_GSWF, atchan->mask);
> +	while (!(at_xdmac_chan_read(atchan, AT_XDMAC_CIS) & AT_XDMAC_CIS_FIS))
> +		cpu_relax();
> +
> +	cur_nda = at_xdmac_chan_read(atchan, AT_XDMAC_CNDA) & 0xfffffffc;
> +	/*
> +	 * Remove size of all microblocks already transferred and the current
> +	 * one. Then add the remaining size to transfer of the current
> +	 * microblock.
> +	 */
> +	descs_list = &desc->descs_list;
> +	list_for_each_entry_safe(desc, _desc, descs_list, desc_node) {
> +		residue -= (desc->lld.mbr_ubc & 0xffffff) << atchan->dwidth;
> +		if ((desc->lld.mbr_nda & 0xfffffffc) == cur_nda)
> +			break;
> +	}
> +	residue += at_xdmac_chan_read(atchan, AT_XDMAC_CUBC) << atchan->dwidth;
> +
> +	spin_unlock_irqrestore(&atchan->lock, flags);
> +
> +	dma_set_residue(txstate, residue);
> +
> +	dev_dbg(chan2dev(chan),
> +		 "%s: desc=0x%p, tx_dma_desc.phys=0x%08x, tx_status=%d, cookie=%d, residue=%d\n",
> +		 __func__, desc, desc->tx_dma_desc.phys, ret, cookie, residue);
> +
> +	return ret;
> +}
> +
> +static void at_xdmac_remove_xfer(struct at_xdmac_chan *atchan,
> +				    struct at_xdmac_desc *desc)
> +{
> +	dev_dbg(chan2dev(&atchan->chan), "%s: desc 0x%p\n", __func__, desc);
> +
> +	/*
> +	 * Remove the transfer from the transfer list then move the transfer
> +	 * descriptors into the free descriptors list.
> +	 */
> +	list_del(&desc->xfer_node);
> +	list_splice_init(&desc->descs_list, &atchan->free_descs_list);
> +}
> +
> +static void at_xdmac_advance_work(struct at_xdmac_chan *atchan)
> +{
> +	struct at_xdmac_desc	*desc;
> +	unsigned long		flags;
> +
> +	spin_lock_irqsave(&atchan->lock, flags);
> +
> +	/*
> +	 * If channel is enabled, do nothing, advance_work will be triggered
> +	 * after the interruption.
> +	 */
> +	if (!at_xdmac_chan_is_enabled(atchan) && !list_empty(&atchan->xfers_list)) {
> +		desc = list_first_entry(&atchan->xfers_list,
> +					struct at_xdmac_desc,
> +					xfer_node);
> +		dev_vdbg(chan2dev(&atchan->chan), "%s: desc 0x%p\n", __func__, desc);
> +		if (!desc->active_xfer)
> +			at_xdmac_start_xfer(atchan, desc);
> +	}
> +
> +	spin_unlock_irqrestore(&atchan->lock, flags);
> +}
> +
> +static void at_xdmac_handle_cyclic(struct at_xdmac_chan *atchan)
> +{
> +	struct at_xdmac_desc		*desc;
> +	struct dma_async_tx_descriptor	*txd;
> +
> +	desc = list_first_entry(&atchan->xfers_list, struct at_xdmac_desc, xfer_node);
> +	txd = &desc->tx_dma_desc;
> +
> +	if (txd->callback && (txd->flags & DMA_PREP_INTERRUPT))
> +		txd->callback(txd->callback_param);
> +}
> +
> +static void at_xdmac_tasklet(unsigned long data)
> +{
> +	struct at_xdmac_chan	*atchan = (struct at_xdmac_chan *)data;
> +	struct at_xdmac_desc	*desc;
> +	u32			error_mask;
> +
> +	dev_dbg(chan2dev(&atchan->chan), "%s: status=0x%08lx\n",
> +		 __func__, atchan->status);
> +
> +	error_mask = AT_XDMAC_CIS_RBEIS
> +		     | AT_XDMAC_CIS_WBEIS
> +		     | AT_XDMAC_CIS_ROIS;
> +
> +	if (at_xdmac_chan_is_cyclic(atchan)) {
> +		at_xdmac_handle_cyclic(atchan);
> +	} else if ((atchan->status & AT_XDMAC_CIS_LIS)
> +		   || (atchan->status & error_mask)) {
> +		struct dma_async_tx_descriptor  *txd;
> +
> +		if (atchan->status & AT_XDMAC_CIS_RBEIS)
> +			dev_err(chan2dev(&atchan->chan), "read bus error!!!");
> +		else if (atchan->status & AT_XDMAC_CIS_WBEIS)
> +			dev_err(chan2dev(&atchan->chan), "write bus error!!!");
> +		else if (atchan->status & AT_XDMAC_CIS_ROIS)
> +			dev_err(chan2dev(&atchan->chan), "request overflow error!!!");
> +
> +		desc = list_first_entry(&atchan->xfers_list,
> +					struct at_xdmac_desc,
> +					xfer_node);
> +		dev_vdbg(chan2dev(&atchan->chan), "%s: desc 0x%p\n", __func__, desc);
> +		BUG_ON(!desc->active_xfer);
> +
> +		txd = &desc->tx_dma_desc;
> +
> +		at_xdmac_remove_xfer(atchan, desc);
> +
> +		if (!at_xdmac_chan_is_cyclic(atchan)) {
> +			dma_cookie_complete(txd);
> +			if (txd->callback && (txd->flags & DMA_PREP_INTERRUPT))
> +				txd->callback(txd->callback_param);
> +		}
> +
> +		dma_run_dependencies(txd);
> +
> +		at_xdmac_advance_work(atchan);
> +	}
> +}
> +
> +static irqreturn_t at_xdmac_interrupt(int irq, void *dev_id)
> +{
> +	struct at_xdmac		*atxdmac = (struct at_xdmac *)dev_id;
> +	struct at_xdmac_chan	*atchan;
> +	u32 			imr, status, pending;
> +	u32			chan_imr, chan_status;
> +	int			i, ret = IRQ_NONE;
> +
> +	do {
> +		imr = at_xdmac_read(atxdmac, AT_XDMAC_GIM);
> +		status = at_xdmac_read(atxdmac, AT_XDMAC_GIS);
> +		pending = status & imr;
> +
> +		dev_vdbg(atxdmac->dma.dev,
> +			 "%s: status=0x%08x, imr=0x%08x, pending=0x%08x\n",
> +			 __func__, status, imr, pending);
> +
> +		if (!pending)
> +			break;
> +
> +		/* We have to find which channel has generated the interrupt. */
> +		for (i = 0; i < atxdmac->dma.chancnt; i++) {
> +			if (!((1 << i) & pending))
> +				continue;
> +
> +			atchan = &atxdmac->chan[i];
> +			chan_imr = at_xdmac_chan_read(atchan, AT_XDMAC_CIM);
> +			chan_status = at_xdmac_chan_read(atchan, AT_XDMAC_CIS);
> +			atchan->status = chan_status & chan_imr;
> +			dev_vdbg(atxdmac->dma.dev,
> +				 "%s: chan%d: imr=0x%x, status=0x%x\n",
> +				 __func__, i, chan_imr, chan_status);
> +			dev_vdbg(chan2dev(&atchan->chan),
> +				 "%s: XDMAC_CC=0x%08x XDMAC_CNDA=0x%08x, "
> +				 "XDMAC_CNDC=0x%08x, XDMAC_CSA=0x%08x, "
> +				 "XDMAC_CDA=0x%08x, XDMAC_CUBC=0x%08x\n",
> +				 __func__,
> +				 at_xdmac_chan_read(atchan, AT_XDMAC_CC),
> +				 at_xdmac_chan_read(atchan, AT_XDMAC_CNDA),
> +				 at_xdmac_chan_read(atchan, AT_XDMAC_CNDC),
> +				 at_xdmac_chan_read(atchan, AT_XDMAC_CSA),
> +				 at_xdmac_chan_read(atchan, AT_XDMAC_CDA),
> +				 at_xdmac_chan_read(atchan, AT_XDMAC_CUBC));
> +
> +			if (atchan->status & (AT_XDMAC_CIS_RBEIS | AT_XDMAC_CIS_WBEIS))
> +				at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask);
> +
> +			tasklet_schedule(&atchan->tasklet);
> +			ret = IRQ_HANDLED;
> +		}
> +
> +	} while (pending);
> +
> +	return ret;
> +}
> +
> +static void at_xdmac_issue_pending(struct dma_chan *chan)
> +{
> +	struct at_xdmac_chan *atchan = to_at_xdmac_chan(chan);
> +
> +	dev_dbg(chan2dev(&atchan->chan), "%s\n", __func__);
> +
> +	if (!at_xdmac_chan_is_cyclic(atchan))
> +		at_xdmac_advance_work(atchan);
> +
> +	return;
> +}
> +
> +static int at_xdmac_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
> +			    unsigned long arg)
> +{
> +	struct at_xdmac_desc	*desc, *_desc;
> +	struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);
> +	struct at_xdmac		*atxdmac = to_at_xdmac(atchan->chan.device);
> +	unsigned long		flags;
> +	int			ret = 0;
> +
> +	dev_dbg(chan2dev(chan), "%s: cmd=%d\n", __func__, cmd);
> +
> +	spin_lock_irqsave(&atchan->lock, flags);
> +
> +	switch (cmd) {
> +	case DMA_PAUSE:
> +		at_xdmac_write(atxdmac, AT_XDMAC_GRWS, atchan->mask);
> +		set_bit(AT_XDMAC_CHAN_IS_PAUSED, &atchan->status);
> +		break;
> +
> +	case DMA_RESUME:
> +		if (!at_xdmac_chan_is_paused(atchan))
> +			break;
> +
> +		at_xdmac_write(atxdmac, AT_XDMAC_GRWR, atchan->mask);
> +		clear_bit(AT_XDMAC_CHAN_IS_PAUSED, &atchan->status);
> +		break;
> +
> +	case DMA_TERMINATE_ALL:
> +		at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask);
> +		while (at_xdmac_read(atxdmac, AT_XDMAC_GS) & atchan->mask)
> +			cpu_relax();
> +
> +		/* Cancel all pending transfers. */
> +		list_for_each_entry_safe(desc, _desc, &atchan->xfers_list, xfer_node)
> +			at_xdmac_remove_xfer(atchan, desc);
> +
> +		clear_bit(AT_XDMAC_CHAN_IS_CYCLIC, &atchan->status);
> +		break;
> +
> +	case DMA_SLAVE_CONFIG:
> +		ret = at_xdmac_set_slave_config(chan,
> +				(struct dma_slave_config *)arg);
> +		break;
> +
> +	default:
> +		dev_err(chan2dev(chan),
> +			"unmanaged or unknown dma control cmd: %d\n", cmd);
> +		ret = -ENXIO;
> +	}
> +
> +	spin_unlock_irqrestore(&atchan->lock, flags);
> +
> +	return ret;
> +}
> +
> +static int at_xdmac_alloc_chan_resources(struct dma_chan *chan)
> +{
> +	struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);
> +	struct at_xdmac_desc	*desc;
> +	unsigned long		flags;
> +	int			i;
> +
> +	spin_lock_irqsave(&atchan->lock, flags);
> +
> +	if (at_xdmac_chan_is_enabled(atchan)) {
> +		dev_err(chan2dev(chan),
> +			"can't allocate channel resources (channel enabled)\n");
> +		i = -EIO;
> +		goto spin_unlock;
> +	}
> +
> +	if (!list_empty(&atchan->free_descs_list)) {
> +		dev_err(chan2dev(chan),
> +			"can't allocate channel resources (channel not free from a previous use)\n");
> +		i = -EIO;
> +		goto spin_unlock;
> +	}
> +
> +	for (i = 0; i < init_nr_desc_per_channel; i++) {
> +		desc = at_xdmac_alloc_desc(chan, GFP_ATOMIC);
> +		if (!desc) {
> +			dev_warn(chan2dev(chan),
> +				"only %d descriptors have been allocated\n", i);
> +			break;
> +		}
> +		list_add_tail(&desc->desc_node, &atchan->free_descs_list);
> +	}
> +
> +	dma_cookie_init(chan);
> +
> +	dev_dbg(chan2dev(chan), "%s: allocated %d descriptors\n", __func__, i);
> +
> +spin_unlock:
> +	spin_unlock_irqrestore(&atchan->lock, flags);
> +	return i;
> +}
> +
> +static void at_xdmac_free_chan_resources(struct dma_chan *chan)
> +{
> +	struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);
> +	struct at_xdmac		*atxdmac = to_at_xdmac(chan->device);
> +	struct at_xdmac_desc	*desc, *_desc;
> +
> +	list_for_each_entry_safe(desc, _desc, &atchan->free_descs_list, desc_node) {
> +		dev_dbg(chan2dev(chan), "%s: freeing descriptor %p\n", __func__, desc);
> +		list_del(&desc->desc_node);
> +		dma_pool_free(atxdmac->at_xdmac_desc_pool, desc, desc->tx_dma_desc.phys);
> +	}
> +
> +	return;
> +}
> +
> +#define AT_XDMAC_DMA_BUSWIDTHS\
> +	(BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED) |\
> +	BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |\
> +	BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |\
> +	BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) |\
> +	BIT(DMA_SLAVE_BUSWIDTH_8_BYTES))
> +
> +static int at_xdmac_device_slave_caps(struct dma_chan *dchan,
> +				      struct dma_slave_caps *caps)
> +{
> +
> +	caps->src_addr_widths = AT_XDMAC_DMA_BUSWIDTHS;
> +	caps->dstn_addr_widths = AT_XDMAC_DMA_BUSWIDTHS;
> +	caps->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
> +	caps->cmd_pause = true;
> +	caps->cmd_terminate = true;
> +	caps->residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM
> +static int atmel_xdmac_prepare(struct device *dev)
> +{
> +	struct platform_device	*pdev = to_platform_device(dev);
> +	struct at_xdmac		*atxdmac = platform_get_drvdata(pdev);
> +	struct dma_chan		*chan, *_chan;
> +
> +	list_for_each_entry_safe(chan, _chan, &atxdmac->dma.channels, device_node) {
> +		struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);
> +
> +		/* Wait for transfer completion, except in cyclic case. */
> +		if (at_xdmac_chan_is_enabled(atchan) && !at_xdmac_chan_is_cyclic(atchan))
> +			return -EAGAIN;
> +	}
> +	return 0;
> +}
> +#else
> +#	define atmel_xdmac_prepare NULL
> +#endif
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int atmel_xdmac_suspend(struct device *dev)
> +{
> +	struct platform_device	*pdev = to_platform_device(dev);
> +	struct at_xdmac		*atxdmac = platform_get_drvdata(pdev);
> +	struct dma_chan		*chan, *_chan;
> +
> +	list_for_each_entry_safe(chan, _chan, &atxdmac->dma.channels, device_node) {
> +		struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);
> +
> +		if (at_xdmac_chan_is_cyclic(atchan)) {
> +			if (!at_xdmac_chan_is_paused(atchan))
> +				at_xdmac_control(chan, DMA_PAUSE, 0);
> +			atchan->save_cim = at_xdmac_chan_read(atchan, AT_XDMAC_CIM);
> +			atchan->save_cnda = at_xdmac_chan_read(atchan, AT_XDMAC_CNDA);
> +			atchan->save_cndc = at_xdmac_chan_read(atchan, AT_XDMAC_CNDC);
> +		}
> +	}
> +	atxdmac->save_gim = at_xdmac_read(atxdmac, AT_XDMAC_GIM);
> +
> +	at_xdmac_off(atxdmac);
> +	clk_disable_unprepare(atxdmac->clk);
> +	return 0;
> +}
> +
> +static int atmel_xdmac_resume(struct device *dev)
> +{
> +	struct platform_device	*pdev = to_platform_device(dev);
> +	struct at_xdmac		*atxdmac = platform_get_drvdata(pdev);
> +	struct at_xdmac_chan	*atchan;
> +	struct dma_chan		*chan, *_chan;
> +	int			i;
> +
> +	clk_prepare_enable(atxdmac->clk);
> +
> +	/* Clear pending interrupts. */
> +	for (i = 0; i < atxdmac->dma.chancnt; i++) {
> +		atchan = &atxdmac->chan[i];
> +		while (at_xdmac_chan_read(atchan, AT_XDMAC_CIS))
> +			cpu_relax();
> +	}
> +
> +	at_xdmac_write(atxdmac, AT_XDMAC_GIE, atxdmac->save_gim);
> +	at_xdmac_write(atxdmac, AT_XDMAC_GE, atxdmac->save_gs);
> +	list_for_each_entry_safe(chan, _chan, &atxdmac->dma.channels, device_node) {
> +		atchan = to_at_xdmac_chan(chan);
> +		at_xdmac_chan_write(atchan, AT_XDMAC_CC, atchan->cfg);
> +		if (at_xdmac_chan_is_cyclic(atchan)) {
> +			at_xdmac_chan_write(atchan, AT_XDMAC_CNDA, atchan->save_cnda);
> +			at_xdmac_chan_write(atchan, AT_XDMAC_CNDC, atchan->save_cndc);
> +			at_xdmac_chan_write(atchan, AT_XDMAC_CIE, atchan->save_cim);
> +			wmb();
> +			at_xdmac_write(atxdmac, AT_XDMAC_GE, atchan->mask);
> +		}
> +	}
> +	return 0;
> +}
> +#endif /* CONFIG_PM_SLEEP */
> +
> +static int at_xdmac_probe(struct platform_device *pdev)
> +{
> +	struct resource	*res;
> +	struct at_xdmac	*atxdmac;
> +	int		irq, size, nr_channels, i, ret;
> +	void __iomem	*base;
> +	u32		reg;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -EINVAL;
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0)
> +		return irq;
> +
> +	base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	/*
> +	 * Read number of xdmac channels, read helper function can't be used
> +	 * since atxdmac is not yet allocated and we need to know the number
> +	 * of channels to do the allocation.
> +	 */
> +	reg = readl_relaxed(base + AT_XDMAC_GTYPE);
> +	nr_channels = AT_XDMAC_NB_CH(reg);
> +	if (nr_channels > AT_XDMAC_MAX_CHAN) {
> +		dev_err(&pdev->dev, "invalid number of channels (%u)\n",
> +			nr_channels);
> +		return -EINVAL;
> +	}
> +
> +	size = sizeof(*atxdmac);
> +	size += nr_channels * sizeof(struct at_xdmac_chan);
> +	atxdmac = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
> +	if (!atxdmac) {
> +		dev_err(&pdev->dev, "can't allocate at_xdmac structure\n");
> +		return -ENOMEM;
> +	}
> +
> +	atxdmac->regs = base;
> +	atxdmac->irq = irq;
> +
> +	atxdmac->clk = devm_clk_get(&pdev->dev, "dma_clk");
> +	if (IS_ERR(atxdmac->clk)) {
> +		dev_err(&pdev->dev, "can't get dma_clk\n");
> +		return PTR_ERR(atxdmac->clk);
> +	}
> +
> +	/* Do not use dev res to prevent races with tasklet */
> +	ret = request_irq(atxdmac->irq, at_xdmac_interrupt, 0, "at_xdmac", atxdmac);
> +	if (ret) {
> +		dev_err(&pdev->dev, "can't request irq\n");
> +		return ret;
> +	}
> +
> +	ret = clk_prepare_enable(atxdmac->clk);
> +	if (ret) {
> +		dev_err(&pdev->dev, "can't prepare or enable clock\n");
> +		goto err_free_irq;
> +	}
> +
> +	atxdmac->at_xdmac_desc_pool =
> +		dmam_pool_create(dev_name(&pdev->dev), &pdev->dev,
> +				sizeof(struct at_xdmac_desc), 4, 0);
> +	if (!atxdmac->at_xdmac_desc_pool) {
> +		dev_err(&pdev->dev, "no memory for descriptors dma pool\n");
> +		ret = -ENOMEM;
> +		goto err_clk_disable;
> +	}
> +
> +	dma_cap_set(DMA_CYCLIC, atxdmac->dma.cap_mask);
> +	dma_cap_set(DMA_MEMCPY, atxdmac->dma.cap_mask);
> +	dma_cap_set(DMA_SLAVE, atxdmac->dma.cap_mask);
> +	atxdmac->dma.dev				= &pdev->dev;
> +	atxdmac->dma.device_alloc_chan_resources	= at_xdmac_alloc_chan_resources;
> +	atxdmac->dma.device_free_chan_resources		= at_xdmac_free_chan_resources;
> +	atxdmac->dma.device_tx_status			= at_xdmac_tx_status;
> +	atxdmac->dma.device_issue_pending		= at_xdmac_issue_pending;
> +	atxdmac->dma.device_prep_dma_cyclic		= at_xdmac_prep_dma_cyclic;
> +	atxdmac->dma.device_prep_dma_memcpy		= at_xdmac_prep_dma_memcpy;
> +	atxdmac->dma.device_prep_slave_sg		= at_xdmac_prep_slave_sg;
> +	atxdmac->dma.device_control			= at_xdmac_control;
> +	atxdmac->dma.chancnt				= nr_channels;
> +	atxdmac->dma.device_slave_caps			= at_xdmac_device_slave_caps;
> +
> +	/* Disable all chans and interrupts. */
> +	at_xdmac_off(atxdmac);
> +
> +	/* Init channels. */
> +	INIT_LIST_HEAD(&atxdmac->dma.channels);
> +	for (i = 0; i < nr_channels; i++) {
> +		struct at_xdmac_chan *atchan = &atxdmac->chan[i];
> +
> +		atchan->chan.device = &atxdmac->dma;
> +		list_add_tail(&atchan->chan.device_node,
> +			      &atxdmac->dma.channels);
> +
> +		atchan->ch_regs = at_xdmac_chan_reg_base(atxdmac, i);
> +		atchan->mask = 1 << i;
> +
> +		spin_lock_init(&atchan->lock);
> +		INIT_LIST_HEAD(&atchan->xfers_list);
> +		INIT_LIST_HEAD(&atchan->free_descs_list);
> +		tasklet_init(&atchan->tasklet, at_xdmac_tasklet,
> +			     (unsigned long)atchan);
> +
> +		/* Clear pending interrupts. */
> +		while (at_xdmac_chan_read(atchan, AT_XDMAC_CIS))
> +			cpu_relax();
> +	}
> +	platform_set_drvdata(pdev, atxdmac);
> +
> +	ret = dma_async_device_register(&atxdmac->dma);
> +	if (ret) {
> +		dev_err(&pdev->dev, "fail to register DMA engine device\n");
> +		goto err_clk_disable;
> +	}
> +
> +	ret = of_dma_controller_register(pdev->dev.of_node,
> +					 at_xdmac_xlate, atxdmac);
> +	if (ret) {
> +		dev_err(&pdev->dev, "could not register of dma controller\n");
> +		goto err_dma_unregister;
> +	}
> +
> +	dev_info(&pdev->dev, "%d channels, mapped at 0x%p\n",
> +		 nr_channels, atxdmac->regs);
> +
> +	return 0;
> +
> +err_dma_unregister:
> +	dma_async_device_unregister(&atxdmac->dma);
> +err_clk_disable:
> +	clk_disable_unprepare(atxdmac->clk);
> +err_free_irq:
> +	free_irq(atxdmac->irq, atxdmac->dma.dev);
> +	return ret;
> +}
> +
> +static int at_xdmac_remove(struct platform_device *pdev)
> +{
> +	struct at_xdmac	*atxdmac = (struct at_xdmac *)platform_get_drvdata(pdev);
> +	int		i;
> +
> +	at_xdmac_off(atxdmac);
> +	of_dma_controller_free(pdev->dev.of_node);
> +	dma_async_device_unregister(&atxdmac->dma);
> +	clk_disable_unprepare(atxdmac->clk);
> +
> +	synchronize_irq(atxdmac->irq);
> +
> +	free_irq(atxdmac->irq, atxdmac->dma.dev);
> +
> +	for (i = 0; i < atxdmac->dma.chancnt; i++) {
> +		struct at_xdmac_chan *atchan = &atxdmac->chan[i];
> +
> +		tasklet_kill(&atchan->tasklet);
> +		at_xdmac_free_chan_resources(&atchan->chan);
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops atmel_xdmac_dev_pm_ops = {
> +	.prepare	= atmel_xdmac_prepare,
> +	SET_LATE_SYSTEM_SLEEP_PM_OPS(atmel_xdmac_suspend, atmel_xdmac_resume)
> +};
> +
> +static const struct of_device_id atmel_xdmac_dt_ids[] = {
> +	{
> +		.compatible = "atmel,sama5d4-dma",
> +	}, {
> +		/* sentinel */
> +	}
> +};
> +MODULE_DEVICE_TABLE(of, atmel_xdmac_dt_ids);
> +
> +static struct platform_driver at_xdmac_driver = {
> +	.probe		= at_xdmac_probe,
> +	.remove		= at_xdmac_remove,
> +	.driver = {
> +		.name		= "at_xdmac",
> +		.owner		= THIS_MODULE,
> +		.of_match_table	= of_match_ptr(atmel_xdmac_dt_ids),
> +		.pm		= &atmel_xdmac_dev_pm_ops,
> +	}
> +};
> +
> +static int __init at_xdmac_init(void)
> +{
> +	return platform_driver_probe(&at_xdmac_driver, at_xdmac_probe);
> +}
> +subsys_initcall(at_xdmac_init);
> +
> +MODULE_DESCRIPTION("Atmel Extended DMA Controller driver");
> +MODULE_AUTHOR("Ludovic Desroches <[e-mail]>");
> +MODULE_LICENSE("GPL");
> diff --git a/include/dt-bindings/dma/at91.h b/include/dt-bindings/dma/at91.h
> index e835037..4875a50 100644
> --- a/include/dt-bindings/dma/at91.h
> +++ b/include/dt-bindings/dma/at91.h
> @@ -9,6 +9,8 @@
>  #ifndef __DT_BINDINGS_AT91_DMA_H__
>  #define __DT_BINDINGS_AT91_DMA_H__
>  
> +/* ---------- HDMAC ---------- */
> +
>  /*
>   * Source and/or destination peripheral ID
>   */
> @@ -24,4 +26,27 @@
>  #define AT91_DMA_CFG_FIFOCFG_ALAP	(0x1 << AT91_DMA_CFG_FIFOCFG_OFFSET)	/* largest defined AHB burst */
>  #define AT91_DMA_CFG_FIFOCFG_ASAP	(0x2 << AT91_DMA_CFG_FIFOCFG_OFFSET)	/* single AHB access */
>  
> +
> +/* ---------- XDMAC ---------- */
> +#define AT91_XDMAC_DT_MEM_IF_MASK	(0x1)
> +#define AT91_XDMAC_DT_MEM_IF_OFFSET	(16)
> +#define AT91_XDMAC_DT_MEM_IF(mem_if)	(((mem_if) & AT91_XDMAC_DT_MEM_IF_MASK) \
> +					<< AT91_XDMAC_DT_MEM_IF_OFFSET)
> +#define AT91_XDMAC_DT_GET_MEM_IF(cfg)	(((cfg) >> AT91_XDMAC_DT_MEM_IF_OFFSET) \
> +					& AT91_XDMAC_DT_MEM_IF_MASK)
> +
> +#define AT91_XDMAC_DT_PER_IF_MASK	(0x1)
> +#define AT91_XDMAC_DT_PER_IF_OFFSET	(0)
> +#define AT91_XDMAC_DT_PER_IF(per_if)	(((per_if) & AT91_XDMAC_DT_PER_IF_MASK) \
> +					<< AT91_XDMAC_DT_PER_IF_OFFSET)
> +#define AT91_XDMAC_DT_GET_PER_IF(cfg)	(((cfg) >> AT91_XDMAC_DT_PER_IF_OFFSET) \
> +					& AT91_XDMAC_DT_PER_IF_MASK)
> +
> +#define AT91_XDMAC_DT_PERID_MASK	(0x7f)
> +#define AT91_XDMAC_DT_PERID_OFFSET	(24)
> +#define AT91_XDMAC_DT_PERID(perid)	(((perid) & AT91_XDMAC_DT_PERID_MASK) \
> +					<< AT91_XDMAC_DT_PERID_OFFSET)
> +#define AT91_XDMAC_DT_GET_PERID(cfg)	(((cfg) >> AT91_XDMAC_DT_PERID_OFFSET) \
> +					& AT91_XDMAC_DT_PERID_MASK)
> +
>  #endif /* __DT_BINDINGS_AT91_DMA_H__ */
>

Patch

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 9b1ea0e..042ebb1 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -107,6 +107,13 @@  config AT_HDMAC
 	help
 	  Support the Atmel AHB DMA controller.
 
+config AT_XDMAC
+	tristate "Atmel XDMA support"
+	depends on (ARCH_AT91 || COMPILE_TEST)
+	select DMA_ENGINE
+	help
+	  Support the Atmel XDMA controller.
+
 config FSL_DMA
 	tristate "Freescale Elo series DMA support"
 	depends on FSL_SOC
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index c6adb92..f32bfe1 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -17,6 +17,7 @@  obj-$(CONFIG_PPC_BESTCOMM) += bestcomm/
 obj-$(CONFIG_MV_XOR) += mv_xor.o
 obj-$(CONFIG_DW_DMAC_CORE) += dw/
 obj-$(CONFIG_AT_HDMAC) += at_hdmac.o
+obj-$(CONFIG_AT_XDMAC) += at_xdmac.o
 obj-$(CONFIG_MX3_IPU) += ipu/
 obj-$(CONFIG_TXX9_DMAC) += txx9dmac.o
 obj-$(CONFIG_SH_DMAE_BASE) += sh/
diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
new file mode 100644
index 0000000..b05e259
--- /dev/null
+++ b/drivers/dma/at_xdmac.c
@@ -0,0 +1,1491 @@ 
+/*
+ * Driver for the Atmel Extensible DMA Controller (aka XDMAC on AT91 systems)
+ *
+ * Copyright (C) 2014 Atmel Corporation
+ *
+ * Author: Ludovic Desroches <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <asm/barrier.h>
+#include <dt-bindings/dma/at91.h>
+#include <linux/clk.h>
+#include <linux/dmaengine.h>
+#include <linux/dmapool.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/of_dma.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+
+#include "dmaengine.h"
+
+/* Global registers */
+#define AT_XDMAC_GTYPE		0x00	/* Global Type Register */
+#define		AT_XDMAC_NB_CH(i)	(((i) & 0x1F) + 1)		/* Number of Channels Minus One */
+#define		AT_XDMAC_FIFO_SZ(i)	(((i) >> 5) & 0x7FF)		/* Number of Bytes */
+#define		AT_XDMAC_NB_REQ(i)	((((i) >> 16) & 0x3F) + 1)	/* Number of Peripheral Requests Minus One */
+#define AT_XDMAC_GCFG		0x04	/* Global Configuration Register */
+#define AT_XDMAC_GWAC		0x08	/* Global Weighted Arbiter Configuration Register */
+#define AT_XDMAC_GIE		0x0C	/* Global Interrupt Enable Register */
+#define AT_XDMAC_GID		0x10	/* Global Interrupt Disable Register */
+#define AT_XDMAC_GIM		0x14	/* Global Interrupt Mask Register */
+#define AT_XDMAC_GIS		0x18	/* Global Interrupt Status Register */
+#define AT_XDMAC_GE		0x1C	/* Global Channel Enable Register */
+#define AT_XDMAC_GD		0x20	/* Global Channel Disable Register */
+#define AT_XDMAC_GS		0x24	/* Global Channel Status Register */
+#define AT_XDMAC_GRS		0x28	/* Global Channel Read Suspend Register */
+#define AT_XDMAC_GWS		0x2C	/* Global Write Suspend Register */
+#define AT_XDMAC_GRWS		0x30	/* Global Channel Read Write Suspend Register */
+#define AT_XDMAC_GRWR		0x34	/* Global Channel Read Write Resume Register */
+#define AT_XDMAC_GSWR		0x38	/* Global Channel Software Request Register */
+#define AT_XDMAC_GSWS		0x3C	/* Global channel Software Request Status Register */
+#define AT_XDMAC_GSWF		0x40	/* Global Channel Software Flush Request Register */
+#define AT_XDMAC_VERSION	0xFFC	/* XDMAC Version Register */
+
+/* Channel relative registers offsets */
+#define AT_XDMAC_CIE		0x00	/* Channel Interrupt Enable Register */
+#define		AT_XDMAC_CIE_BIE	BIT(0)	/* End of Block Interrupt Enable Bit */
+#define		AT_XDMAC_CIE_LIE	BIT(1)	/* End of Linked List Interrupt Enable Bit */
+#define		AT_XDMAC_CIE_DIE	BIT(2)	/* End of Disable Interrupt Enable Bit */
+#define		AT_XDMAC_CIE_FIE	BIT(3)	/* End of Flush Interrupt Enable Bit */
+#define		AT_XDMAC_CIE_RBEIE	BIT(4)	/* Read Bus Error Interrupt Enable Bit */
+#define		AT_XDMAC_CIE_WBEIE	BIT(5)	/* Write Bus Error Interrupt Enable Bit */
+#define		AT_XDMAC_CIE_ROIE	BIT(6)	/* Request Overflow Interrupt Enable Bit */
+#define AT_XDMAC_CID		0x04	/* Channel Interrupt Disable Register */
+#define		AT_XDMAC_CID_BID	BIT(0)	/* End of Block Interrupt Disable Bit */
+#define		AT_XDMAC_CID_LID	BIT(1)	/* End of Linked List Interrupt Disable Bit */
+#define		AT_XDMAC_CID_DID	BIT(2)	/* End of Disable Interrupt Disable Bit */
+#define		AT_XDMAC_CID_FID	BIT(3)	/* End of Flush Interrupt Disable Bit */
+#define		AT_XDMAC_CID_RBEID	BIT(4)	/* Read Bus Error Interrupt Disable Bit */
+#define		AT_XDMAC_CID_WBEID	BIT(5)	/* Write Bus Error Interrupt Disable Bit */
+#define		AT_XDMAC_CID_ROID	BIT(6)	/* Request Overflow Interrupt Disable Bit */
+#define AT_XDMAC_CIM		0x08	/* Channel Interrupt Mask Register */
+#define		AT_XDMAC_CIM_BIM	BIT(0)	/* End of Block Interrupt Mask Bit */
+#define		AT_XDMAC_CIM_LIM	BIT(1)	/* End of Linked List Interrupt Mask Bit */
+#define		AT_XDMAC_CIM_DIM	BIT(2)	/* End of Disable Interrupt Mask Bit */
+#define		AT_XDMAC_CIM_FIM	BIT(3)	/* End of Flush Interrupt Mask Bit */
+#define		AT_XDMAC_CIM_RBEIM	BIT(4)	/* Read Bus Error Interrupt Mask Bit */
+#define		AT_XDMAC_CIM_WBEIM	BIT(5)	/* Write Bus Error Interrupt Mask Bit */
+#define		AT_XDMAC_CIM_ROIM	BIT(6)	/* Request Overflow Interrupt Mask Bit */
+#define AT_XDMAC_CIS		0x0C	/* Channel Interrupt Status Register */
+#define		AT_XDMAC_CIS_BIS	BIT(0)	/* End of Block Interrupt Status Bit */
+#define		AT_XDMAC_CIS_LIS	BIT(1)	/* End of Linked List Interrupt Status Bit */
+#define		AT_XDMAC_CIS_DIS	BIT(2)	/* End of Disable Interrupt Status Bit */
+#define		AT_XDMAC_CIS_FIS	BIT(3)	/* End of Flush Interrupt Status Bit */
+#define		AT_XDMAC_CIS_RBEIS	BIT(4)	/* Read Bus Error Interrupt Status Bit */
+#define		AT_XDMAC_CIS_WBEIS	BIT(5)	/* Write Bus Error Interrupt Status Bit */
+#define		AT_XDMAC_CIS_ROIS	BIT(6)	/* Request Overflow Interrupt Status Bit */
+#define AT_XDMAC_CSA		0x10	/* Channel Source Address Register */
+#define AT_XDMAC_CDA		0x14	/* Channel Destination Address Register */
+#define AT_XDMAC_CNDA		0x18	/* Channel Next Descriptor Address Register */
+#define 	AT_XDMAC_CNDA_NDAIF(i)	((i) & 0x1)			/* Channel x Next Descriptor Interface */
+#define		AT_XDMAC_CNDA_NDA(i)	((i) & 0xfffffffc)		/* Channel x Next Descriptor Address */
+#define AT_XDMAC_CNDC		0x1C	/* Channel Next Descriptor Control Register */
+#define		AT_XDMAC_CNDC_NDE		(0x1 << 0)		/* Channel x Next Descriptor Enable */
+#define		AT_XDMAC_CNDC_NDSUP		(0x1 << 1)		/* Channel x Next Descriptor Source Update */
+#define		AT_XDMAC_CNDC_NDDUP		(0x1 << 2)		/* Channel x Next Descriptor Destination Update */
+#define		AT_XDMAC_CNDC_NDVIEW_NDV0	(0x0 << 3)		/* Channel x Next Descriptor View 0 */
+#define		AT_XDMAC_CNDC_NDVIEW_NDV1	(0x1 << 3)		/* Channel x Next Descriptor View 1 */
+#define		AT_XDMAC_CNDC_NDVIEW_NDV2	(0x2 << 3)		/* Channel x Next Descriptor View 2 */
+#define		AT_XDMAC_CNDC_NDVIEW_NDV3	(0x3 << 3)		/* Channel x Next Descriptor View 3 */
+#define AT_XDMAC_CUBC		0x20	/* Channel Microblock Control Register */
+#define AT_XDMAC_CBC		0x24	/* Channel Block Control Register */
+#define AT_XDMAC_CC		0x28	/* Channel Configuration Register */
+#define		AT_XDMAC_CC_TYPE	(0x1 << 0)	/* Channel Transfer Type */
+#define			AT_XDMAC_CC_TYPE_MEM_TRAN	(0x0 << 0)	/* Memory to Memory Transfer */
+#define			AT_XDMAC_CC_TYPE_PER_TRAN	(0x1 << 0)	/* Peripheral to Memory or Memory to Peripheral Transfer */
+#define		AT_XDMAC_CC_MBSIZE_MASK	(0x3 << 1)
+#define			AT_XDMAC_CC_MBSIZE_SINGLE	(0x0 << 1)
+#define			AT_XDMAC_CC_MBSIZE_FOUR		(0x1 << 1)
+#define			AT_XDMAC_CC_MBSIZE_EIGHT	(0x2 << 1)
+#define			AT_XDMAC_CC_MBSIZE_SIXTEEN	(0x3 << 1)
+#define		AT_XDMAC_CC_DSYNC	(0x1 << 4)	/* Channel Synchronization */
+#define			AT_XDMAC_CC_DSYNC_PER2MEM	(0x0 << 4)
+#define			AT_XDMAC_CC_DSYNC_MEM2PER	(0x1 << 4)
+#define		AT_XDMAC_CC_PROT	(0x1 << 5)	/* Channel Protection */
+#define			AT_XDMAC_CC_PROT_SEC		(0x0 << 5)
+#define			AT_XDMAC_CC_PROT_UNSEC		(0x1 << 5)
+#define		AT_XDMAC_CC_SWREQ	(0x1 << 6)	/* Channel Software Request Trigger */
+#define			AT_XDMAC_CC_SWREQ_HWR_CONNECTED	(0x0 << 6)
+#define			AT_XDMAC_CC_SWREQ_SWR_CONNECTED	(0x1 << 6)
+#define		AT_XDMAC_CC_MEMSET	(0x1 << 7)	/* Channel Fill Block of memory */
+#define			AT_XDMAC_CC_MEMSET_NORMAL_MODE	(0x0 << 7)
+#define			AT_XDMAC_CC_MEMSET_HW_MODE	(0x1 << 7)
+#define		AT_XDMAC_CC_CSIZE_MASK	(0x7 << 8)	/* Channel Chunk Size */
+#define			AT_XDMAC_CC_CSIZE_CHK_1		(0x0 << 8)
+#define			AT_XDMAC_CC_CSIZE_CHK_2		(0x1 << 8)
+#define			AT_XDMAC_CC_CSIZE_CHK_4		(0x2 << 8)
+#define			AT_XDMAC_CC_CSIZE_CHK_8		(0x3 << 8)
+#define			AT_XDMAC_CC_CSIZE_CHK_16	(0x4 << 8)
+#define		AT_XDMAC_CC_DWIDTH(i)	((i) << 11)	/* Channel Data Width */
+#define			AT_XDMAC_CC_DWIDTH_BYTE		0x0
+#define			AT_XDMAC_CC_DWIDTH_HALFWORD	0x1
+#define			AT_XDMAC_CC_DWIDTH_WORD		0x2
+#define			AT_XDMAC_CC_DWIDTH_DWORD	0x3
+#define		AT_XDMAC_CC_SIF(i)	((0x1 & (i)) << 13)	/* Channel Source Interface Identifier */
+#define		AT_XDMAC_CC_DIF(i)	((0x1 & (i)) << 14)	/* Channel Destination Interface Identifier */
+#define		AT_XDMAC_CC_SAM_MASK	(0x3 << 16)	/* Channel Source Addressing Mode */
+#define			AT_XDMAC_CC_SAM_FIXED_AM	(0x0 << 16)
+#define			AT_XDMAC_CC_SAM_INCREMENTED_AM	(0x1 << 16)
+#define			AT_XDMAC_CC_SAM_UBS_AM		(0x2 << 16)
+#define			AT_XDMAC_CC_SAM_UBS_DS_AM	(0x3 << 16)
+#define		AT_XDMAC_CC_DAM_MASK	(0x3 << 18)	/* Channel Source Addressing Mode */
+#define			AT_XDMAC_CC_DAM_FIXED_AM	(0x0 << 18)
+#define			AT_XDMAC_CC_DAM_INCREMENTED_AM	(0x1 << 18)
+#define			AT_XDMAC_CC_DAM_UBS_AM		(0x2 << 18)
+#define			AT_XDMAC_CC_DAM_UBS_DS_AM	(0x3 << 18)
+#define		AT_XDMAC_CC_INITD	(0x1 << 21)	/* Channel Initialization Terminated (read only) */
+#define			AT_XDMAC_CC_INITD_TERMINATED	(0x0 << 21)
+#define			AT_XDMAC_CC_INITD_IN_PROGRESS	(0x1 << 21)
+#define		AT_XDMAC_CC_RDIP	(0x1 << 22)	/* Read in Progress (read only) */
+#define			AT_XDMAC_CC_RDIP_DONE		(0x0 << 22)
+#define			AT_XDMAC_CC_RDIP_IN_PROGRESS	(0x1 << 22)
+#define		AT_XDMAC_CC_WRIP	(0x1 << 23)	/* Write in Progress (read only) */
+#define			AT_XDMAC_CC_WRIP_DONE		(0x0 << 23)
+#define			AT_XDMAC_CC_WRIP_IN_PROGRESS	(0x1 << 23)
+#define		AT_XDMAC_CC_PERID(i)	(0x7f & (h) << 24)	/* Channel Peripheral Identifier */
+#define AT_XDMAC_CDS_MSP	0x2C	/* Channel Data Stride Memory Set Pattern */
+#define AT_XDMAC_CSUS		0x30	/* Channel Source Microblock Stride */
+#define AT_XDMAC_CDUS		0x34	/* Channel Destination Microblock Stride */
+
+#define AT_XDMAC_CHAN_REG_BASE	0x50	/* Channel registers base address */
+
+/* Microblock control members */
+#define AT_XDMAC_MBR_UBC_UBLEN_MAX	0xFFFFFFUL	/* Maximum Microblock Length */
+#define AT_XDMAC_MBR_UBC_NDE		(0x1 << 24)	/* Next Descriptor Enable */
+#define AT_XDMAC_MBR_UBC_NSEN		(0x1 << 25)	/* Next Descriptor Source Update */
+#define AT_XDMAC_MBR_UBC_NDEN		(0x1 << 26)	/* Next Descriptor Destination Update */
+#define AT_XDMAC_MBR_UBC_NDV0		(0x0 << 27)	/* Next Descriptor View 0 */
+#define AT_XDMAC_MBR_UBC_NDV1		(0x1 << 27)	/* Next Descriptor View 1 */
+#define AT_XDMAC_MBR_UBC_NDV2		(0x2 << 27)	/* Next Descriptor View 2 */
+#define AT_XDMAC_MBR_UBC_NDV3		(0x3 << 27)	/* Next Descriptor View 3 */
+
+#define AT_XDMAC_MAX_CHAN	0x20
+
+enum atc_status {
+	AT_XDMAC_CHAN_IS_CYCLIC = 0,
+	AT_XDMAC_CHAN_IS_PAUSED,
+};
+
+/* ----- Channels ----- */
+struct at_xdmac_chan {
+	struct dma_chan		chan;
+	void __iomem		*ch_regs;
+	u32			mask;		/* Channel Mask */
+	u32			cfg;		/* Channel Configuration Register */
+	u8			perid;		/* Peripheral ID */
+	u8			dwidth;		/* Data Width */
+	u8			perif;		/* Peripheral Interface */
+	u8			memif;		/* Memory Interface */
+	u32			save_cim;
+	u32			save_cnda;
+	u32			save_cndc;
+	unsigned long		status;
+	struct tasklet_struct	tasklet;
+	struct dma_slave_config	dma_sconfig;
+
+	spinlock_t		lock;
+
+	struct list_head	xfers_list;
+	struct list_head	free_descs_list;
+};
+
+
+/* ----- Controller ----- */
+struct at_xdmac {
+	struct dma_device	dma;
+	void __iomem		*regs;
+	int			irq;
+	struct clk		*clk;
+	u32			save_gim;
+	u32			save_gs;
+	struct dma_pool		*at_xdmac_desc_pool;
+	struct at_xdmac_chan	chan[0];
+};
+
+
+/* ----- Descriptors ----- */
+
+/* Linked List Descriptor */
+struct at_xdmac_lld {
+	dma_addr_t	mbr_nda;	/* Next Descriptor Member */
+	u32		mbr_ubc;	/* Microblock Control Member */
+	dma_addr_t	mbr_sa;		/* Source Address Member */
+	dma_addr_t	mbr_da;		/* Destination Address Member */
+	u32		mbr_cfg;	/* Configuration Register */
+};
+
+
+struct at_xdmac_desc {
+	struct at_xdmac_lld		lld;
+	enum dma_transfer_direction	direction;
+	struct dma_async_tx_descriptor	tx_dma_desc;
+	struct list_head		desc_node;
+	/* Following members are only used by the first descriptor */
+	bool				active_xfer;
+	unsigned int			xfer_size;
+	struct list_head		descs_list;
+	struct list_head		xfer_node;
+};
+
+static inline void __iomem *at_xdmac_chan_reg_base(struct at_xdmac *atxdmac, unsigned int chan_nb)
+{
+	return atxdmac->regs + (AT_XDMAC_CHAN_REG_BASE + chan_nb * 0x40);
+}
+
+#define at_xdmac_read(atxdmac, reg) readl_relaxed((atxdmac)->regs + (reg))
+#define at_xdmac_write(atxdmac, reg, value) \
+	writel_relaxed((value), (atxdmac)->regs + (reg))
+
+#define at_xdmac_chan_read(atchan, reg) readl_relaxed((atchan)->ch_regs + (reg))
+#define at_xdmac_chan_write(atchan, reg, value) writel_relaxed((value), (atchan)->ch_regs + (reg))
+
+static inline struct at_xdmac_chan *to_at_xdmac_chan(struct dma_chan *dchan)
+{
+	return container_of(dchan, struct at_xdmac_chan, chan);
+}
+
+static struct device *chan2dev(struct dma_chan *chan)
+{
+	return &chan->dev->device;
+}
+
+static inline struct at_xdmac *to_at_xdmac(struct dma_device *ddev)
+{
+	return container_of(ddev, struct at_xdmac, dma);
+}
+
+static inline struct at_xdmac_desc *txd_to_at_desc(struct dma_async_tx_descriptor *txd)
+{
+	return container_of(txd, struct at_xdmac_desc, tx_dma_desc);
+}
+
+static inline int at_xdmac_chan_is_cyclic(struct at_xdmac_chan *atchan)
+{
+	return test_bit(AT_XDMAC_CHAN_IS_CYCLIC, &atchan->status);
+}
+
+static inline int at_xdmac_chan_is_paused(struct at_xdmac_chan *atchan)
+{
+	return test_bit(AT_XDMAC_CHAN_IS_PAUSED, &atchan->status);
+}
+
+static inline u32 at_xdmac_csize(u32 maxburst)
+{
+	u32 csize;
+
+	switch (ffs(maxburst) - 1) {
+	case 1:
+		csize = AT_XDMAC_CC_CSIZE_CHK_2;
+		break;
+	case 2:
+		csize = AT_XDMAC_CC_CSIZE_CHK_4;
+		break;
+	case 3:
+		csize = AT_XDMAC_CC_CSIZE_CHK_8;
+		break;
+	case 4:
+		csize = AT_XDMAC_CC_CSIZE_CHK_16;
+		break;
+	default:
+		csize = AT_XDMAC_CC_CSIZE_CHK_1;
+	}
+
+	return csize;
+};
+
+static unsigned int init_nr_desc_per_channel = 64;
+module_param(init_nr_desc_per_channel, uint, 0644);
+MODULE_PARM_DESC(init_nr_desc_per_channel,
+		 "initial descriptors per channel (default: 64)");
+
+
+static bool at_xdmac_chan_is_enabled(struct at_xdmac_chan *atchan)
+{
+	return at_xdmac_chan_read(atchan, AT_XDMAC_GS) & atchan->mask;
+}
+
+static void at_xdmac_off(struct at_xdmac *atxdmac)
+{
+	at_xdmac_write(atxdmac, AT_XDMAC_GD, -1L);
+
+	/* Wait that all chans are disabled. */
+	while (at_xdmac_read(atxdmac, AT_XDMAC_GS))
+		cpu_relax();
+
+	at_xdmac_write(atxdmac, AT_XDMAC_GID, -1L);
+}
+
+/* Call with lock hold. */
+static void at_xdmac_start_xfer(struct at_xdmac_chan *atchan,
+				struct at_xdmac_desc *first)
+{
+	struct at_xdmac	*atxdmac = to_at_xdmac(atchan->chan.device);
+	u32		reg;
+
+	dev_vdbg(chan2dev(&atchan->chan), "%s: desc 0x%p\n", __func__, first);
+
+	if (at_xdmac_chan_is_enabled(atchan))
+		return;
+
+	/* Set transfer as active to not try to start it again. */
+	first->active_xfer = true;
+
+	/* Tell xdmac where to get the first descriptor. */
+	reg = AT_XDMAC_CNDA_NDA(first->tx_dma_desc.phys)
+	      | AT_XDMAC_CNDA_NDAIF(atchan->memif);
+	at_xdmac_chan_write(atchan, AT_XDMAC_CNDA, reg);
+
+	/*
+	 * When doing memory to memory transfer we need to use the next
+	 * descriptor view 2 since some fields of the configuration register
+	 * depend on transfer size and src/dest addresses.
+	 */
+	if (atchan->cfg & AT_XDMAC_CC_TYPE_PER_TRAN) {
+		reg = AT_XDMAC_CNDC_NDVIEW_NDV1;
+		at_xdmac_chan_write(atchan, AT_XDMAC_CC, atchan->cfg);
+	} else {
+		reg = AT_XDMAC_CNDC_NDVIEW_NDV2;
+	}
+
+	reg |= AT_XDMAC_CNDC_NDDUP
+	       | AT_XDMAC_CNDC_NDSUP
+	       | AT_XDMAC_CNDC_NDE;
+	at_xdmac_chan_write(atchan, AT_XDMAC_CNDC, reg);
+
+	dev_vdbg(chan2dev(&atchan->chan),
+		 "%s: XDMAC_CC=0x%08x XDMAC_CNDA=0x%08x, XDMAC_CNDC=0x%08x, "
+		 "XDMAC_CSA=0x%08x, XDMAC_CDA=0x%08x, XDMAC_CUBC=0x%08x\n",
+		 __func__, at_xdmac_chan_read(atchan, AT_XDMAC_CC),
+		 at_xdmac_chan_read(atchan, AT_XDMAC_CNDA),
+		 at_xdmac_chan_read(atchan, AT_XDMAC_CNDC),
+		 at_xdmac_chan_read(atchan, AT_XDMAC_CSA),
+		 at_xdmac_chan_read(atchan, AT_XDMAC_CDA),
+		 at_xdmac_chan_read(atchan, AT_XDMAC_CUBC));
+
+	/*
+	 * There is no end of list when doing cyclic dma, we need to get
+	 * an interrupt after each periods.
+	 */
+	if (at_xdmac_chan_is_cyclic(atchan))
+		at_xdmac_chan_write(atchan, AT_XDMAC_CIE, AT_XDMAC_CIE_BIE);
+	else
+		at_xdmac_chan_write(atchan, AT_XDMAC_CIE, AT_XDMAC_CIE_LIE);
+	at_xdmac_write(atxdmac, AT_XDMAC_GIE, atchan->mask);
+	dev_vdbg(chan2dev(&atchan->chan),
+		 "%s: enable channel (0x%08x)\n", __func__, atchan->mask);
+	wmb();
+	at_xdmac_write(atxdmac, AT_XDMAC_GE, atchan->mask);
+
+	dev_vdbg(chan2dev(&atchan->chan),
+		 "%s: XDMAC_CC=0x%08x XDMAC_CNDA=0x%08x, XDMAC_CNDC=0x%08x, "
+		 "XDMAC_CSA=0x%08x, XDMAC_CDA=0x%08x, XDMAC_CUBC=0x%08x\n",
+		 __func__, at_xdmac_chan_read(atchan, AT_XDMAC_CC),
+		 at_xdmac_chan_read(atchan, AT_XDMAC_CNDA),
+		 at_xdmac_chan_read(atchan, AT_XDMAC_CNDC),
+		 at_xdmac_chan_read(atchan, AT_XDMAC_CSA),
+		 at_xdmac_chan_read(atchan, AT_XDMAC_CDA),
+		 at_xdmac_chan_read(atchan, AT_XDMAC_CUBC));
+
+}
+
+static dma_cookie_t at_xdmac_tx_submit(struct dma_async_tx_descriptor *tx)
+{
+	struct at_xdmac_desc	*desc = txd_to_at_desc(tx);
+	struct at_xdmac_chan	*atchan = to_at_xdmac_chan(tx->chan);
+	dma_cookie_t		cookie;
+	unsigned long		flags;
+
+	spin_lock_irqsave(&atchan->lock, flags);
+	cookie = dma_cookie_assign(tx);
+
+	dev_vdbg(chan2dev(tx->chan), "%s: atchan 0x%p, add desc 0x%p to xfers_list\n",
+		 __func__, atchan, desc);
+	list_add_tail(&desc->xfer_node, &atchan->xfers_list);
+	if (list_is_singular(&atchan->xfers_list))
+		at_xdmac_start_xfer(atchan, desc);
+
+	spin_unlock_irqrestore(&atchan->lock, flags);
+	return cookie;
+}
+
+static struct at_xdmac_desc *at_xdmac_alloc_desc(struct dma_chan *chan,
+						 gfp_t gfp_flags)
+{
+	struct at_xdmac_desc	*desc;
+	struct at_xdmac		*atxdmac = to_at_xdmac(chan->device);
+	dma_addr_t		phys;
+
+	desc = dma_pool_alloc(atxdmac->at_xdmac_desc_pool, gfp_flags, &phys);
+	if (desc) {
+		memset(desc, 0, sizeof(*desc));
+		INIT_LIST_HEAD(&desc->descs_list);
+		dma_async_tx_descriptor_init(&desc->tx_dma_desc, chan);
+		desc->tx_dma_desc.tx_submit = at_xdmac_tx_submit;
+		desc->tx_dma_desc.phys = phys;
+	}
+
+	return desc;
+}
+
+/* Call must be protected by lock. */
+static struct at_xdmac_desc *at_xdmac_get_desc(struct at_xdmac_chan *atchan)
+{
+	struct at_xdmac_desc *desc;
+
+	if (list_empty(&atchan->free_descs_list)) {
+		desc = at_xdmac_alloc_desc(&atchan->chan, GFP_NOWAIT);
+	} else {
+		desc = list_first_entry(&atchan->free_descs_list,
+					struct at_xdmac_desc, desc_node);
+		list_del(&desc->desc_node);
+		desc->active_xfer = false;
+	}
+
+	return desc;
+}
+
+static struct dma_chan *at_xdmac_xlate(struct of_phandle_args *dma_spec,
+				       struct of_dma *of_dma)
+{
+	struct at_xdmac		*atxdmac = of_dma->of_dma_data;
+	struct at_xdmac_chan	*atchan;
+	struct dma_chan		*chan;
+	struct device		*dev = atxdmac->dma.dev;
+
+	if (dma_spec->args_count != 2) {
+		dev_err(dev, "dma phandler args: bad number of args\n");
+		return NULL;
+	}
+
+	chan = dma_get_any_slave_channel(&atxdmac->dma);
+	if (!chan) {
+		dev_err(dev, "can't get a dma channel\n");
+		return NULL;
+	}
+
+	atchan = to_at_xdmac_chan(chan);
+	atchan->memif = AT91_XDMAC_DT_GET_MEM_IF(dma_spec->args[0]);
+	atchan->perif = AT91_XDMAC_DT_GET_PER_IF(dma_spec->args[0]);
+	atchan->perid = AT91_XDMAC_DT_GET_PERID(dma_spec->args[1]);
+	dev_dbg(dev, "chan dt cfg: memif=%u perif=%u perid=%u\n",
+		 atchan->memif, atchan->perif, atchan->perid);
+
+	return chan;
+}
+
+static int at_xdmac_set_slave_config(struct dma_chan *chan,
+				      struct dma_slave_config *sconfig)
+{
+	struct at_xdmac_chan 	*atchan = to_at_xdmac_chan(chan);
+
+	atchan->cfg = AT91_XDMAC_DT_PERID(atchan->perid)
+		      |	AT_XDMAC_CC_SWREQ_HWR_CONNECTED
+		      | AT_XDMAC_CC_MBSIZE_SIXTEEN
+		      | AT_XDMAC_CC_TYPE_PER_TRAN;
+
+	if (sconfig->direction == DMA_DEV_TO_MEM) {
+		atchan->cfg |= AT_XDMAC_CC_DAM_INCREMENTED_AM
+			       | AT_XDMAC_CC_SAM_FIXED_AM
+			       | AT_XDMAC_CC_DIF(atchan->memif)
+			       | AT_XDMAC_CC_SIF(atchan->perif)
+			       | AT_XDMAC_CC_DSYNC_PER2MEM;
+		atchan->dwidth = ffs(sconfig->src_addr_width) - 1;
+		atchan->cfg |= AT_XDMAC_CC_DWIDTH(atchan->dwidth);
+		atchan->cfg |= at_xdmac_csize(sconfig->src_maxburst);
+	} else if (sconfig->direction == DMA_MEM_TO_DEV) {
+		atchan->cfg |= AT_XDMAC_CC_DAM_FIXED_AM
+			       | AT_XDMAC_CC_SAM_INCREMENTED_AM
+			       | AT_XDMAC_CC_DIF(atchan->perif)
+			       | AT_XDMAC_CC_SIF(atchan->memif)
+			       | AT_XDMAC_CC_DSYNC_MEM2PER;
+		atchan->dwidth = ffs(sconfig->dst_addr_width) - 1;
+		atchan->cfg |= AT_XDMAC_CC_DWIDTH(atchan->dwidth);
+		atchan->cfg |= at_xdmac_csize(sconfig->dst_maxburst);
+	} else {
+		return -EINVAL;
+	}
+
+	/*
+	 * Src address and dest addr are needed to configure the link list
+	 * descriptor so keep the slave configuration.
+	 */
+	memcpy(&atchan->dma_sconfig, sconfig, sizeof(struct dma_slave_config));
+
+	dev_dbg(chan2dev(chan), "%s: atchan->cfg=0x%08x\n", __func__, atchan->cfg);
+
+	return 0;
+}
+
+static struct dma_async_tx_descriptor *
+at_xdmac_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
+		       unsigned int sg_len, enum dma_transfer_direction direction,
+		       unsigned long flags, void *context)
+{
+	struct at_xdmac_chan 	*atchan = to_at_xdmac_chan(chan);
+	struct dma_slave_config	*sconfig = &atchan->dma_sconfig;
+	struct at_xdmac_desc	*first = NULL, *prev = NULL;
+	struct scatterlist	*sg;
+	int 			i;
+
+	if (!sgl)
+		return NULL;
+
+	if (!is_slave_direction(direction)) {
+		dev_err(chan2dev(chan), "invalid DMA direction\n");
+		return NULL;
+	}
+
+	dev_dbg(chan2dev(chan), "%s: sg_len=%d, dir=%s, flags=0x%lx\n",
+		 __func__, sg_len,
+		 direction == DMA_MEM_TO_DEV ? "to device" : "from device",
+		 flags);
+
+	/* Protect dma_sconfig field that can be modified by set_slave_conf. */
+	spin_lock(&atchan->lock);
+
+	/* Prepare descriptors. */
+	for_each_sg(sgl, sg, sg_len, i) {
+		struct at_xdmac_desc	*desc = NULL;
+		u32			len, mem;
+
+		len = sg_dma_len(sg);
+		mem = sg_dma_address(sg);
+		if (unlikely(!len)) {
+			dev_err(chan2dev(chan), "sg data length is zero\n");
+			spin_unlock(&atchan->lock);
+			return NULL;
+		}
+		dev_dbg(chan2dev(chan), "%s: * sg%d len=%u, mem=0x%08x\n",
+			 __func__, i, len, mem);
+
+		desc = at_xdmac_get_desc(atchan);
+		if (!desc) {
+			dev_err(chan2dev(chan), "can't get descriptor\n");
+			if (first)
+				list_splice_init(&first->descs_list, &atchan->free_descs_list);
+			spin_unlock(&atchan->lock);
+			return NULL;
+		}
+
+		/* Linked list descriptor setup. */
+		if (direction == DMA_DEV_TO_MEM) {
+			desc->lld.mbr_sa = sconfig->src_addr;
+			desc->lld.mbr_da = mem;
+		} else {
+			desc->lld.mbr_sa = mem;
+			desc->lld.mbr_da = sconfig->dst_addr;
+		}
+		desc->lld.mbr_ubc = AT_XDMAC_MBR_UBC_NDV1		/* next descriptor view */
+			| AT_XDMAC_MBR_UBC_NDEN				/* next descriptor dst parameter update */
+			| AT_XDMAC_MBR_UBC_NSEN				/* next descriptor src parameter update */
+			| (i == sg_len - 1 ? 0 : AT_XDMAC_MBR_UBC_NDE)	/* descriptor fetch */
+			| len / (1 << atchan->dwidth);			/* microblock length */
+		dev_dbg(chan2dev(chan),
+			 "%s: lld: mbr_sa=0x%08x, mbr_da=0x%08x, mbr_ubc=0x%08x\n",
+			 __func__, desc->lld.mbr_sa, desc->lld.mbr_da, desc->lld.mbr_ubc);
+
+		/* Chain lld. */
+		if (prev) {
+			prev->lld.mbr_nda = desc->tx_dma_desc.phys;
+			dev_dbg(chan2dev(chan),
+				 "%s: chain lld: prev=0x%p, mbr_nda=0x%08x\n",
+				 __func__, prev, prev->lld.mbr_nda);
+		}
+
+		prev = desc;
+		if (!first)
+			first = desc;
+
+		dev_dbg(chan2dev(chan), "%s: add desc 0x%p to descs_list 0x%p\n",
+			 __func__, desc, first);
+		list_add_tail(&desc->desc_node, &first->descs_list);
+	}
+
+	spin_unlock(&atchan->lock);
+
+	first->tx_dma_desc.cookie = -EBUSY;
+	first->tx_dma_desc.flags = flags;
+	first->xfer_size = sg_len;
+
+	return &first->tx_dma_desc;
+}
+
+static struct dma_async_tx_descriptor *
+at_xdmac_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t buf_addr,
+			 size_t buf_len, size_t period_len,
+			 enum dma_transfer_direction direction,
+			 unsigned long flags)
+{
+	struct at_xdmac_chan 	*atchan = to_at_xdmac_chan(chan);
+	struct dma_slave_config	*sconfig = &atchan->dma_sconfig;
+	struct at_xdmac_desc	*first = NULL, *prev = NULL;
+	unsigned int		periods = buf_len / period_len;
+	unsigned long		lock_flags;
+	int 			i;
+
+	dev_dbg(chan2dev(chan), "%s: buf_addr=0x%08x, buf_len=%d, period_len=%d, "
+		"dir=%s, flags=0x%lx\n",
+		__func__, buf_addr, buf_len, period_len,
+		direction == DMA_MEM_TO_DEV ? "mem2per" : "per2mem", flags);
+
+	if (!is_slave_direction(direction)) {
+		dev_err(chan2dev(chan), "invalid DMA direction\n");
+		return NULL;
+	}
+
+	if (test_and_set_bit(AT_XDMAC_CHAN_IS_CYCLIC, &atchan->status)) {
+		dev_err(chan2dev(chan), "channel currently used\n");
+		return NULL;
+	}
+
+	for (i = 0; i < periods; i++) {
+		struct at_xdmac_desc	*desc = NULL;
+
+		spin_lock_irqsave(&atchan->lock, lock_flags);
+		desc = at_xdmac_get_desc(atchan);
+		spin_unlock_irqrestore(&atchan->lock, lock_flags);
+		if (!desc) {
+			dev_err(chan2dev(chan), "can't get descriptor\n");
+			if (first)
+				list_splice_init(&first->descs_list, &atchan->free_descs_list);
+			return NULL;
+		}
+		dev_dbg(chan2dev(chan),
+			"%s: desc=0x%p, tx_dma_desc.phys=0x%08x\n",
+			__func__, desc, desc->tx_dma_desc.phys);
+
+		if (direction == DMA_DEV_TO_MEM) {
+			desc->lld.mbr_sa = sconfig->src_addr;
+			desc->lld.mbr_da = buf_addr + i * period_len;
+		} else {
+			desc->lld.mbr_sa = buf_addr + i * period_len;
+			desc->lld.mbr_da = sconfig->dst_addr;
+		};
+		desc->lld.mbr_ubc = AT_XDMAC_MBR_UBC_NDV1
+			| AT_XDMAC_MBR_UBC_NDEN
+			| AT_XDMAC_MBR_UBC_NSEN
+			| AT_XDMAC_MBR_UBC_NDE
+			| period_len >> atchan->dwidth;
+
+		dev_dbg(chan2dev(chan),
+			 "%s: lld: mbr_sa=0x%08x, mbr_da=0x%08x, mbr_ubc=0x%08x\n",
+			 __func__, desc->lld.mbr_sa, desc->lld.mbr_da, desc->lld.mbr_ubc);
+
+		/* Chain lld. */
+		if (prev) {
+			prev->lld.mbr_nda = desc->tx_dma_desc.phys;
+			dev_dbg(chan2dev(chan),
+				 "%s: chain lld: prev=0x%p, mbr_nda=0x%08x\n",
+				 __func__, prev, prev->lld.mbr_nda);
+		}
+
+		prev = desc;
+		if (!first)
+			first = desc;
+
+		dev_dbg(chan2dev(chan), "%s: add desc 0x%p to descs_list 0x%p\n",
+			 __func__, desc, first);
+		list_add_tail(&desc->desc_node, &first->descs_list);
+	}
+
+	prev->lld.mbr_nda = first->tx_dma_desc.phys;
+	dev_dbg(chan2dev(chan),
+		"%s: chain lld: prev=0x%p, mbr_nda=0x%08x\n",
+		__func__, prev, prev->lld.mbr_nda);
+	first->tx_dma_desc.cookie = -EBUSY;
+	first->tx_dma_desc.flags = flags;
+	first->xfer_size = buf_len;
+
+	return &first->tx_dma_desc;
+}
+
+static struct dma_async_tx_descriptor *
+at_xdmac_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
+			 size_t len, unsigned long flags)
+{
+	struct at_xdmac_chan 	*atchan = to_at_xdmac_chan(chan);
+	struct at_xdmac_desc	*first = NULL, *prev = NULL;
+	size_t			remaining_size = len, xfer_size = 0, ublen;
+	dma_addr_t		src_addr = src, dst_addr = dest;
+	u32			dwidth;
+	/*
+	 * WARNING: The channel configuration is set here since there is no
+	 * dmaengine_slave_config call in this case. Moreover we don't know the
+	 * direction, it involves we can't dynamically set the source and dest
+	 * interface so we have to use the same one. Only interface 0 allows EBI
+	 * access. Hopefully we can access DDR through both ports (at least on
+	 * SAMA5D4x), so we can use the same interface for source and dest,
+	 * that solves the fact we don't know the direction.
+	 */
+	u32			chan_cc = AT_XDMAC_CC_DAM_INCREMENTED_AM
+					| AT_XDMAC_CC_SAM_INCREMENTED_AM
+					| AT_XDMAC_CC_DIF(0)
+					| AT_XDMAC_CC_SIF(0)
+					| AT_XDMAC_CC_MBSIZE_SIXTEEN
+					| AT_XDMAC_CC_TYPE_MEM_TRAN;
+
+	dev_dbg(chan2dev(chan), "%s: src=0x%08x, dest=0x%08x, len=%d, flags=0x%lx\n",
+		__func__, src, dest, len, flags);
+
+	if (unlikely(!len))
+		return NULL;
+
+	/*
+	 * Check address alignment to select the greater data width we can use.
+	 * Some XDMAC implementations don't provide dword transfer, in this
+	 * case selecting dword has the same behavior as selecting word transfers.
+	 */
+	if (!((src_addr | dst_addr) & 7)) {
+		dwidth = AT_XDMAC_CC_DWIDTH_DWORD;
+		dev_dbg(chan2dev(chan), "%s: dwidth: double word\n", __func__);
+	} else if (!((src_addr | dst_addr)  & 3)) {
+		dwidth = AT_XDMAC_CC_DWIDTH_WORD;
+		dev_dbg(chan2dev(chan), "%s: dwidth: word\n", __func__);
+	} else if (!((src_addr | dst_addr) & 1)) {
+		dwidth = AT_XDMAC_CC_DWIDTH_HALFWORD;
+		dev_dbg(chan2dev(chan), "%s: dwidth: half word\n", __func__);
+	} else {
+		dwidth = AT_XDMAC_CC_DWIDTH_BYTE;
+		dev_dbg(chan2dev(chan), "%s: dwidth: byte\n", __func__);
+	}
+
+	atchan->cfg = chan_cc | AT_XDMAC_CC_DWIDTH(dwidth);
+
+	/* Prepare descriptors. */
+	while (remaining_size) {
+		struct at_xdmac_desc	*desc = NULL;
+
+		dev_dbg(chan2dev(chan), "%s: remaining_size=%u\n", __func__, remaining_size);
+
+		spin_lock_irqsave(&atchan->lock, flags);
+		desc = at_xdmac_get_desc(atchan);
+		spin_unlock_irqrestore(&atchan->lock, flags);
+		if (!desc) {
+			dev_err(chan2dev(chan), "can't get descriptor\n");
+			if (first)
+				list_splice_init(&first->descs_list, &atchan->free_descs_list);
+			return NULL;
+		}
+
+		/* Update src and dest addresses. */
+		src_addr += xfer_size;
+		dst_addr += xfer_size;
+
+		if (remaining_size >= AT_XDMAC_MBR_UBC_UBLEN_MAX << dwidth)
+			xfer_size = AT_XDMAC_MBR_UBC_UBLEN_MAX << dwidth;
+		else
+			xfer_size = remaining_size;
+
+		dev_dbg(chan2dev(chan), "%s: xfer_size=%u\n", __func__, xfer_size);
+
+		/* Check remaining length and change data width if needed. */
+		if (!((src_addr | dst_addr | xfer_size) & 7)) {
+			dwidth = AT_XDMAC_CC_DWIDTH_DWORD;
+			dev_dbg(chan2dev(chan), "%s: dwidth: double word\n", __func__);
+		} else if (!((src_addr | dst_addr | xfer_size)  & 3)) {
+			dwidth = AT_XDMAC_CC_DWIDTH_WORD;
+			dev_dbg(chan2dev(chan), "%s: dwidth: word\n", __func__);
+		} else if (!((src_addr | dst_addr | xfer_size) & 1)) {
+			dwidth = AT_XDMAC_CC_DWIDTH_HALFWORD;
+			dev_dbg(chan2dev(chan), "%s: dwidth: half word\n", __func__);
+		} else if ((src_addr | dst_addr | xfer_size) & 1) {
+			dwidth = AT_XDMAC_CC_DWIDTH_BYTE;
+			dev_dbg(chan2dev(chan), "%s: dwidth: byte\n", __func__);
+		}
+		chan_cc |= AT_XDMAC_CC_DWIDTH(dwidth);
+
+		ublen = xfer_size >> dwidth;
+		remaining_size -= xfer_size;
+
+		desc->lld.mbr_sa = src_addr;
+		desc->lld.mbr_da = dst_addr;
+		desc->lld.mbr_ubc = AT_XDMAC_MBR_UBC_NDV2
+			| AT_XDMAC_MBR_UBC_NDEN
+			| AT_XDMAC_MBR_UBC_NSEN
+			| (remaining_size ? 0 : AT_XDMAC_MBR_UBC_NDE)
+			| ublen;
+		desc->lld.mbr_cfg = chan_cc;
+
+		dev_dbg(chan2dev(chan),
+			 "%s: lld: mbr_sa=0x%08x, mbr_da=0x%08x, mbr_ubc=0x%08x, mbr_cfg=0x%08x\n",
+			 __func__, desc->lld.mbr_sa, desc->lld.mbr_da, desc->lld.mbr_ubc, desc->lld.mbr_cfg);
+
+		/* Chain lld. */
+		if (prev) {
+			prev->lld.mbr_nda = desc->tx_dma_desc.phys;
+			dev_dbg(chan2dev(chan),
+				 "%s: chain lld: prev=0x%p, mbr_nda=0x%08x\n",
+				 __func__, prev, prev->lld.mbr_nda);
+		}
+
+		prev = desc;
+		if (!first)
+			first = desc;
+
+		dev_dbg(chan2dev(chan), "%s: add desc 0x%p to descs_list 0x%p\n",
+			 __func__, desc, first);
+		list_add_tail(&desc->desc_node, &first->descs_list);
+	}
+
+	first->tx_dma_desc.cookie = -EBUSY;
+	first->tx_dma_desc.flags = flags;
+	first->xfer_size = len;
+
+	return &first->tx_dma_desc;
+}
+
+static enum dma_status
+at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
+		struct dma_tx_state *txstate)
+{
+	struct at_xdmac_chan 	*atchan = to_at_xdmac_chan(chan);
+	struct at_xdmac		*atxdmac = to_at_xdmac(atchan->chan.device);
+	struct at_xdmac_desc	*desc, *_desc;
+	struct list_head	*descs_list;
+	unsigned long		flags;
+	enum dma_status		ret;
+	int			residue;
+	u32			cur_nda;
+
+	ret = dma_cookie_status(chan, cookie, txstate);
+	if (ret == DMA_COMPLETE)
+		return ret;
+
+	if (!txstate)
+		return ret;
+
+	spin_lock_irqsave(&atchan->lock, flags);
+
+	desc = list_first_entry(&atchan->xfers_list, struct at_xdmac_desc, xfer_node);
+
+	/*
+	 * If the transfer has not been started yet, don't need to compute the
+	 * residue, it's the transfer length.
+	 */
+	if (!desc->active_xfer) {
+		dma_set_residue(txstate, desc->xfer_size);
+		return ret;
+	}
+
+	residue = desc->xfer_size;
+	/* Flush FIFO. */
+	at_xdmac_write(atxdmac, AT_XDMAC_GSWF, atchan->mask);
+	while (!(at_xdmac_chan_read(atchan, AT_XDMAC_CIS) & AT_XDMAC_CIS_FIS))
+		cpu_relax();
+
+	cur_nda = at_xdmac_chan_read(atchan, AT_XDMAC_CNDA) & 0xfffffffc;
+	/*
+	 * Remove size of all microblocks already transferred and the current
+	 * one. Then add the remaining size to transfer of the current
+	 * microblock.
+	 */
+	descs_list = &desc->descs_list;
+	list_for_each_entry_safe(desc, _desc, descs_list, desc_node) {
+		residue -= (desc->lld.mbr_ubc & 0xffffff) << atchan->dwidth;
+		if ((desc->lld.mbr_nda & 0xfffffffc) == cur_nda)
+			break;
+	}
+	residue += at_xdmac_chan_read(atchan, AT_XDMAC_CUBC) << atchan->dwidth;
+
+	spin_unlock_irqrestore(&atchan->lock, flags);
+
+	dma_set_residue(txstate, residue);
+
+	dev_dbg(chan2dev(chan),
+		 "%s: desc=0x%p, tx_dma_desc.phys=0x%08x, tx_status=%d, cookie=%d, residue=%d\n",
+		 __func__, desc, desc->tx_dma_desc.phys, ret, cookie, residue);
+
+	return ret;
+}
+
+static void at_xdmac_remove_xfer(struct at_xdmac_chan *atchan,
+				    struct at_xdmac_desc *desc)
+{
+	dev_dbg(chan2dev(&atchan->chan), "%s: desc 0x%p\n", __func__, desc);
+
+	/*
+	 * Remove the transfer from the transfer list then move the transfer
+	 * descriptors into the free descriptors list.
+	 */
+	list_del(&desc->xfer_node);
+	list_splice_init(&desc->descs_list, &atchan->free_descs_list);
+}
+
+static void at_xdmac_advance_work(struct at_xdmac_chan *atchan)
+{
+	struct at_xdmac_desc	*desc;
+	unsigned long		flags;
+
+	spin_lock_irqsave(&atchan->lock, flags);
+
+	/*
+	 * If channel is enabled, do nothing, advance_work will be triggered
+	 * after the interruption.
+	 */
+	if (!at_xdmac_chan_is_enabled(atchan) && !list_empty(&atchan->xfers_list)) {
+		desc = list_first_entry(&atchan->xfers_list,
+					struct at_xdmac_desc,
+					xfer_node);
+		dev_vdbg(chan2dev(&atchan->chan), "%s: desc 0x%p\n", __func__, desc);
+		if (!desc->active_xfer)
+			at_xdmac_start_xfer(atchan, desc);
+	}
+
+	spin_unlock_irqrestore(&atchan->lock, flags);
+}
+
+static void at_xdmac_handle_cyclic(struct at_xdmac_chan *atchan)
+{
+	struct at_xdmac_desc		*desc;
+	struct dma_async_tx_descriptor	*txd;
+
+	desc = list_first_entry(&atchan->xfers_list, struct at_xdmac_desc, xfer_node);
+	txd = &desc->tx_dma_desc;
+
+	if (txd->callback && (txd->flags & DMA_PREP_INTERRUPT))
+		txd->callback(txd->callback_param);
+}
+
+static void at_xdmac_tasklet(unsigned long data)
+{
+	struct at_xdmac_chan	*atchan = (struct at_xdmac_chan *)data;
+	struct at_xdmac_desc	*desc;
+	u32			error_mask;
+
+	dev_dbg(chan2dev(&atchan->chan), "%s: status=0x%08lx\n",
+		 __func__, atchan->status);
+
+	error_mask = AT_XDMAC_CIS_RBEIS
+		     | AT_XDMAC_CIS_WBEIS
+		     | AT_XDMAC_CIS_ROIS;
+
+	if (at_xdmac_chan_is_cyclic(atchan)) {
+		at_xdmac_handle_cyclic(atchan);
+	} else if ((atchan->status & AT_XDMAC_CIS_LIS)
+		   || (atchan->status & error_mask)) {
+		struct dma_async_tx_descriptor  *txd;
+
+		if (atchan->status & AT_XDMAC_CIS_RBEIS)
+			dev_err(chan2dev(&atchan->chan), "read bus error!!!");
+		else if (atchan->status & AT_XDMAC_CIS_WBEIS)
+			dev_err(chan2dev(&atchan->chan), "write bus error!!!");
+		else if (atchan->status & AT_XDMAC_CIS_ROIS)
+			dev_err(chan2dev(&atchan->chan), "request overflow error!!!");
+
+		desc = list_first_entry(&atchan->xfers_list,
+					struct at_xdmac_desc,
+					xfer_node);
+		dev_vdbg(chan2dev(&atchan->chan), "%s: desc 0x%p\n", __func__, desc);
+		BUG_ON(!desc->active_xfer);
+
+		txd = &desc->tx_dma_desc;
+
+		at_xdmac_remove_xfer(atchan, desc);
+
+		if (!at_xdmac_chan_is_cyclic(atchan)) {
+			dma_cookie_complete(txd);
+			if (txd->callback && (txd->flags & DMA_PREP_INTERRUPT))
+				txd->callback(txd->callback_param);
+		}
+
+		dma_run_dependencies(txd);
+
+		at_xdmac_advance_work(atchan);
+	}
+}
+
+static irqreturn_t at_xdmac_interrupt(int irq, void *dev_id)
+{
+	struct at_xdmac		*atxdmac = (struct at_xdmac *)dev_id;
+	struct at_xdmac_chan	*atchan;
+	u32 			imr, status, pending;
+	u32			chan_imr, chan_status;
+	int			i, ret = IRQ_NONE;
+
+	do {
+		imr = at_xdmac_read(atxdmac, AT_XDMAC_GIM);
+		status = at_xdmac_read(atxdmac, AT_XDMAC_GIS);
+		pending = status & imr;
+
+		dev_vdbg(atxdmac->dma.dev,
+			 "%s: status=0x%08x, imr=0x%08x, pending=0x%08x\n",
+			 __func__, status, imr, pending);
+
+		if (!pending)
+			break;
+
+		/* We have to find which channel has generated the interrupt. */
+		for (i = 0; i < atxdmac->dma.chancnt; i++) {
+			if (!((1 << i) & pending))
+				continue;
+
+			atchan = &atxdmac->chan[i];
+			chan_imr = at_xdmac_chan_read(atchan, AT_XDMAC_CIM);
+			chan_status = at_xdmac_chan_read(atchan, AT_XDMAC_CIS);
+			atchan->status = chan_status & chan_imr;
+			dev_vdbg(atxdmac->dma.dev,
+				 "%s: chan%d: imr=0x%x, status=0x%x\n",
+				 __func__, i, chan_imr, chan_status);
+			dev_vdbg(chan2dev(&atchan->chan),
+				 "%s: XDMAC_CC=0x%08x XDMAC_CNDA=0x%08x, "
+				 "XDMAC_CNDC=0x%08x, XDMAC_CSA=0x%08x, "
+				 "XDMAC_CDA=0x%08x, XDMAC_CUBC=0x%08x\n",
+				 __func__,
+				 at_xdmac_chan_read(atchan, AT_XDMAC_CC),
+				 at_xdmac_chan_read(atchan, AT_XDMAC_CNDA),
+				 at_xdmac_chan_read(atchan, AT_XDMAC_CNDC),
+				 at_xdmac_chan_read(atchan, AT_XDMAC_CSA),
+				 at_xdmac_chan_read(atchan, AT_XDMAC_CDA),
+				 at_xdmac_chan_read(atchan, AT_XDMAC_CUBC));
+
+			if (atchan->status & (AT_XDMAC_CIS_RBEIS | AT_XDMAC_CIS_WBEIS))
+				at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask);
+
+			tasklet_schedule(&atchan->tasklet);
+			ret = IRQ_HANDLED;
+		}
+
+	} while (pending);
+
+	return ret;
+}
+
+static void at_xdmac_issue_pending(struct dma_chan *chan)
+{
+	struct at_xdmac_chan *atchan = to_at_xdmac_chan(chan);
+
+	dev_dbg(chan2dev(&atchan->chan), "%s\n", __func__);
+
+	if (!at_xdmac_chan_is_cyclic(atchan))
+		at_xdmac_advance_work(atchan);
+
+	return;
+}
+
+static int at_xdmac_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
+			    unsigned long arg)
+{
+	struct at_xdmac_desc	*desc, *_desc;
+	struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);
+	struct at_xdmac		*atxdmac = to_at_xdmac(atchan->chan.device);
+	unsigned long		flags;
+	int			ret = 0;
+
+	dev_dbg(chan2dev(chan), "%s: cmd=%d\n", __func__, cmd);
+
+	spin_lock_irqsave(&atchan->lock, flags);
+
+	switch (cmd) {
+	case DMA_PAUSE:
+		at_xdmac_write(atxdmac, AT_XDMAC_GRWS, atchan->mask);
+		set_bit(AT_XDMAC_CHAN_IS_PAUSED, &atchan->status);
+		break;
+
+	case DMA_RESUME:
+		if (!at_xdmac_chan_is_paused(atchan))
+			break;
+
+		at_xdmac_write(atxdmac, AT_XDMAC_GRWR, atchan->mask);
+		clear_bit(AT_XDMAC_CHAN_IS_PAUSED, &atchan->status);
+		break;
+
+	case DMA_TERMINATE_ALL:
+		at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask);
+		while (at_xdmac_read(atxdmac, AT_XDMAC_GS) & atchan->mask)
+			cpu_relax();
+
+		/* Cancel all pending transfers. */
+		list_for_each_entry_safe(desc, _desc, &atchan->xfers_list, xfer_node)
+			at_xdmac_remove_xfer(atchan, desc);
+
+		clear_bit(AT_XDMAC_CHAN_IS_CYCLIC, &atchan->status);
+		break;
+
+	case DMA_SLAVE_CONFIG:
+		ret = at_xdmac_set_slave_config(chan,
+				(struct dma_slave_config *)arg);
+		break;
+
+	default:
+		dev_err(chan2dev(chan),
+			"unmanaged or unknown dma control cmd: %d\n", cmd);
+		ret = -ENXIO;
+	}
+
+	spin_unlock_irqrestore(&atchan->lock, flags);
+
+	return ret;
+}
+
+static int at_xdmac_alloc_chan_resources(struct dma_chan *chan)
+{
+	struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);
+	struct at_xdmac_desc	*desc;
+	unsigned long		flags;
+	int			i;
+
+	spin_lock_irqsave(&atchan->lock, flags);
+
+	if (at_xdmac_chan_is_enabled(atchan)) {
+		dev_err(chan2dev(chan),
+			"can't allocate channel resources (channel enabled)\n");
+		i = -EIO;
+		goto spin_unlock;
+	}
+
+	if (!list_empty(&atchan->free_descs_list)) {
+		dev_err(chan2dev(chan),
+			"can't allocate channel resources (channel not free from a previous use)\n");
+		i = -EIO;
+		goto spin_unlock;
+	}
+
+	for (i = 0; i < init_nr_desc_per_channel; i++) {
+		desc = at_xdmac_alloc_desc(chan, GFP_ATOMIC);
+		if (!desc) {
+			dev_warn(chan2dev(chan),
+				"only %d descriptors have been allocated\n", i);
+			break;
+		}
+		list_add_tail(&desc->desc_node, &atchan->free_descs_list);
+	}
+
+	dma_cookie_init(chan);
+
+	dev_dbg(chan2dev(chan), "%s: allocated %d descriptors\n", __func__, i);
+
+spin_unlock:
+	spin_unlock_irqrestore(&atchan->lock, flags);
+	return i;
+}
+
+static void at_xdmac_free_chan_resources(struct dma_chan *chan)
+{
+	struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);
+	struct at_xdmac		*atxdmac = to_at_xdmac(chan->device);
+	struct at_xdmac_desc	*desc, *_desc;
+
+	list_for_each_entry_safe(desc, _desc, &atchan->free_descs_list, desc_node) {
+		dev_dbg(chan2dev(chan), "%s: freeing descriptor %p\n", __func__, desc);
+		list_del(&desc->desc_node);
+		dma_pool_free(atxdmac->at_xdmac_desc_pool, desc, desc->tx_dma_desc.phys);
+	}
+
+	return;
+}
+
+#define AT_XDMAC_DMA_BUSWIDTHS\
+	(BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED) |\
+	BIT(DMA_SLAVE_BUSWIDTH_1_BYTE) |\
+	BIT(DMA_SLAVE_BUSWIDTH_2_BYTES) |\
+	BIT(DMA_SLAVE_BUSWIDTH_4_BYTES) |\
+	BIT(DMA_SLAVE_BUSWIDTH_8_BYTES))
+
+static int at_xdmac_device_slave_caps(struct dma_chan *dchan,
+				      struct dma_slave_caps *caps)
+{
+
+	caps->src_addr_widths = AT_XDMAC_DMA_BUSWIDTHS;
+	caps->dstn_addr_widths = AT_XDMAC_DMA_BUSWIDTHS;
+	caps->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
+	caps->cmd_pause = true;
+	caps->cmd_terminate = true;
+	caps->residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int atmel_xdmac_prepare(struct device *dev)
+{
+	struct platform_device	*pdev = to_platform_device(dev);
+	struct at_xdmac		*atxdmac = platform_get_drvdata(pdev);
+	struct dma_chan		*chan, *_chan;
+
+	list_for_each_entry_safe(chan, _chan, &atxdmac->dma.channels, device_node) {
+		struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);
+
+		/* Wait for transfer completion, except in cyclic case. */
+		if (at_xdmac_chan_is_enabled(atchan) && !at_xdmac_chan_is_cyclic(atchan))
+			return -EAGAIN;
+	}
+	return 0;
+}
+#else
+#	define atmel_xdmac_prepare NULL
+#endif
+
+#ifdef CONFIG_PM_SLEEP
+static int atmel_xdmac_suspend(struct device *dev)
+{
+	struct platform_device	*pdev = to_platform_device(dev);
+	struct at_xdmac		*atxdmac = platform_get_drvdata(pdev);
+	struct dma_chan		*chan, *_chan;
+
+	list_for_each_entry_safe(chan, _chan, &atxdmac->dma.channels, device_node) {
+		struct at_xdmac_chan	*atchan = to_at_xdmac_chan(chan);
+
+		if (at_xdmac_chan_is_cyclic(atchan)) {
+			if (!at_xdmac_chan_is_paused(atchan))
+				at_xdmac_control(chan, DMA_PAUSE, 0);
+			atchan->save_cim = at_xdmac_chan_read(atchan, AT_XDMAC_CIM);
+			atchan->save_cnda = at_xdmac_chan_read(atchan, AT_XDMAC_CNDA);
+			atchan->save_cndc = at_xdmac_chan_read(atchan, AT_XDMAC_CNDC);
+		}
+	}
+	atxdmac->save_gim = at_xdmac_read(atxdmac, AT_XDMAC_GIM);
+
+	at_xdmac_off(atxdmac);
+	clk_disable_unprepare(atxdmac->clk);
+	return 0;
+}
+
+static int atmel_xdmac_resume(struct device *dev)
+{
+	struct platform_device	*pdev = to_platform_device(dev);
+	struct at_xdmac		*atxdmac = platform_get_drvdata(pdev);
+	struct at_xdmac_chan	*atchan;
+	struct dma_chan		*chan, *_chan;
+	int			i;
+
+	clk_prepare_enable(atxdmac->clk);
+
+	/* Clear pending interrupts. */
+	for (i = 0; i < atxdmac->dma.chancnt; i++) {
+		atchan = &atxdmac->chan[i];
+		while (at_xdmac_chan_read(atchan, AT_XDMAC_CIS))
+			cpu_relax();
+	}
+
+	at_xdmac_write(atxdmac, AT_XDMAC_GIE, atxdmac->save_gim);
+	at_xdmac_write(atxdmac, AT_XDMAC_GE, atxdmac->save_gs);
+	list_for_each_entry_safe(chan, _chan, &atxdmac->dma.channels, device_node) {
+		atchan = to_at_xdmac_chan(chan);
+		at_xdmac_chan_write(atchan, AT_XDMAC_CC, atchan->cfg);
+		if (at_xdmac_chan_is_cyclic(atchan)) {
+			at_xdmac_chan_write(atchan, AT_XDMAC_CNDA, atchan->save_cnda);
+			at_xdmac_chan_write(atchan, AT_XDMAC_CNDC, atchan->save_cndc);
+			at_xdmac_chan_write(atchan, AT_XDMAC_CIE, atchan->save_cim);
+			wmb();
+			at_xdmac_write(atxdmac, AT_XDMAC_GE, atchan->mask);
+		}
+	}
+	return 0;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static int at_xdmac_probe(struct platform_device *pdev)
+{
+	struct resource	*res;
+	struct at_xdmac	*atxdmac;
+	int		irq, size, nr_channels, i, ret;
+	void __iomem	*base;
+	u32		reg;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0)
+		return irq;
+
+	base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	/*
+	 * Read number of xdmac channels, read helper function can't be used
+	 * since atxdmac is not yet allocated and we need to know the number
+	 * of channels to do the allocation.
+	 */
+	reg = readl_relaxed(base + AT_XDMAC_GTYPE);
+	nr_channels = AT_XDMAC_NB_CH(reg);
+	if (nr_channels > AT_XDMAC_MAX_CHAN) {
+		dev_err(&pdev->dev, "invalid number of channels (%u)\n",
+			nr_channels);
+		return -EINVAL;
+	}
+
+	size = sizeof(*atxdmac);
+	size += nr_channels * sizeof(struct at_xdmac_chan);
+	atxdmac = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
+	if (!atxdmac) {
+		dev_err(&pdev->dev, "can't allocate at_xdmac structure\n");
+		return -ENOMEM;
+	}
+
+	atxdmac->regs = base;
+	atxdmac->irq = irq;
+
+	atxdmac->clk = devm_clk_get(&pdev->dev, "dma_clk");
+	if (IS_ERR(atxdmac->clk)) {
+		dev_err(&pdev->dev, "can't get dma_clk\n");
+		return PTR_ERR(atxdmac->clk);
+	}
+
+	/* Do not use dev res to prevent races with tasklet */
+	ret = request_irq(atxdmac->irq, at_xdmac_interrupt, 0, "at_xdmac", atxdmac);
+	if (ret) {
+		dev_err(&pdev->dev, "can't request irq\n");
+		return ret;
+	}
+
+	ret = clk_prepare_enable(atxdmac->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "can't prepare or enable clock\n");
+		goto err_free_irq;
+	}
+
+	atxdmac->at_xdmac_desc_pool =
+		dmam_pool_create(dev_name(&pdev->dev), &pdev->dev,
+				sizeof(struct at_xdmac_desc), 4, 0);
+	if (!atxdmac->at_xdmac_desc_pool) {
+		dev_err(&pdev->dev, "no memory for descriptors dma pool\n");
+		ret = -ENOMEM;
+		goto err_clk_disable;
+	}
+
+	dma_cap_set(DMA_CYCLIC, atxdmac->dma.cap_mask);
+	dma_cap_set(DMA_MEMCPY, atxdmac->dma.cap_mask);
+	dma_cap_set(DMA_SLAVE, atxdmac->dma.cap_mask);
+	atxdmac->dma.dev				= &pdev->dev;
+	atxdmac->dma.device_alloc_chan_resources	= at_xdmac_alloc_chan_resources;
+	atxdmac->dma.device_free_chan_resources		= at_xdmac_free_chan_resources;
+	atxdmac->dma.device_tx_status			= at_xdmac_tx_status;
+	atxdmac->dma.device_issue_pending		= at_xdmac_issue_pending;
+	atxdmac->dma.device_prep_dma_cyclic		= at_xdmac_prep_dma_cyclic;
+	atxdmac->dma.device_prep_dma_memcpy		= at_xdmac_prep_dma_memcpy;
+	atxdmac->dma.device_prep_slave_sg		= at_xdmac_prep_slave_sg;
+	atxdmac->dma.device_control			= at_xdmac_control;
+	atxdmac->dma.chancnt				= nr_channels;
+	atxdmac->dma.device_slave_caps			= at_xdmac_device_slave_caps;
+
+	/* Disable all chans and interrupts. */
+	at_xdmac_off(atxdmac);
+
+	/* Init channels. */
+	INIT_LIST_HEAD(&atxdmac->dma.channels);
+	for (i = 0; i < nr_channels; i++) {
+		struct at_xdmac_chan *atchan = &atxdmac->chan[i];
+
+		atchan->chan.device = &atxdmac->dma;
+		list_add_tail(&atchan->chan.device_node,
+			      &atxdmac->dma.channels);
+
+		atchan->ch_regs = at_xdmac_chan_reg_base(atxdmac, i);
+		atchan->mask = 1 << i;
+
+		spin_lock_init(&atchan->lock);
+		INIT_LIST_HEAD(&atchan->xfers_list);
+		INIT_LIST_HEAD(&atchan->free_descs_list);
+		tasklet_init(&atchan->tasklet, at_xdmac_tasklet,
+			     (unsigned long)atchan);
+
+		/* Clear pending interrupts. */
+		while (at_xdmac_chan_read(atchan, AT_XDMAC_CIS))
+			cpu_relax();
+	}
+	platform_set_drvdata(pdev, atxdmac);
+
+	ret = dma_async_device_register(&atxdmac->dma);
+	if (ret) {
+		dev_err(&pdev->dev, "fail to register DMA engine device\n");
+		goto err_clk_disable;
+	}
+
+	ret = of_dma_controller_register(pdev->dev.of_node,
+					 at_xdmac_xlate, atxdmac);
+	if (ret) {
+		dev_err(&pdev->dev, "could not register of dma controller\n");
+		goto err_dma_unregister;
+	}
+
+	dev_info(&pdev->dev, "%d channels, mapped at 0x%p\n",
+		 nr_channels, atxdmac->regs);
+
+	return 0;
+
+err_dma_unregister:
+	dma_async_device_unregister(&atxdmac->dma);
+err_clk_disable:
+	clk_disable_unprepare(atxdmac->clk);
+err_free_irq:
+	free_irq(atxdmac->irq, atxdmac->dma.dev);
+	return ret;
+}
+
+static int at_xdmac_remove(struct platform_device *pdev)
+{
+	struct at_xdmac	*atxdmac = (struct at_xdmac *)platform_get_drvdata(pdev);
+	int		i;
+
+	at_xdmac_off(atxdmac);
+	of_dma_controller_free(pdev->dev.of_node);
+	dma_async_device_unregister(&atxdmac->dma);
+	clk_disable_unprepare(atxdmac->clk);
+
+	synchronize_irq(atxdmac->irq);
+
+	free_irq(atxdmac->irq, atxdmac->dma.dev);
+
+	for (i = 0; i < atxdmac->dma.chancnt; i++) {
+		struct at_xdmac_chan *atchan = &atxdmac->chan[i];
+
+		tasklet_kill(&atchan->tasklet);
+		at_xdmac_free_chan_resources(&atchan->chan);
+	}
+
+	return 0;
+}
+
+static const struct dev_pm_ops atmel_xdmac_dev_pm_ops = {
+	.prepare	= atmel_xdmac_prepare,
+	SET_LATE_SYSTEM_SLEEP_PM_OPS(atmel_xdmac_suspend, atmel_xdmac_resume)
+};
+
+static const struct of_device_id atmel_xdmac_dt_ids[] = {
+	{
+		.compatible = "atmel,sama5d4-dma",
+	}, {
+		/* sentinel */
+	}
+};
+MODULE_DEVICE_TABLE(of, atmel_xdmac_dt_ids);
+
+static struct platform_driver at_xdmac_driver = {
+	.probe		= at_xdmac_probe,
+	.remove		= at_xdmac_remove,
+	.driver = {
+		.name		= "at_xdmac",
+		.owner		= THIS_MODULE,
+		.of_match_table	= of_match_ptr(atmel_xdmac_dt_ids),
+		.pm		= &atmel_xdmac_dev_pm_ops,
+	}
+};
+
+static int __init at_xdmac_init(void)
+{
+	return platform_driver_probe(&at_xdmac_driver, at_xdmac_probe);
+}
+subsys_initcall(at_xdmac_init);
+
+MODULE_DESCRIPTION("Atmel Extended DMA Controller driver");
+MODULE_AUTHOR("Ludovic Desroches <[e-mail]>");
+MODULE_LICENSE("GPL");
diff --git a/include/dt-bindings/dma/at91.h b/include/dt-bindings/dma/at91.h
index e835037..4875a50 100644
--- a/include/dt-bindings/dma/at91.h
+++ b/include/dt-bindings/dma/at91.h
@@ -9,6 +9,8 @@ 
 #ifndef __DT_BINDINGS_AT91_DMA_H__
 #define __DT_BINDINGS_AT91_DMA_H__
 
+/* ---------- HDMAC ---------- */
+
 /*
  * Source and/or destination peripheral ID
  */
@@ -24,4 +26,27 @@ 
 #define AT91_DMA_CFG_FIFOCFG_ALAP	(0x1 << AT91_DMA_CFG_FIFOCFG_OFFSET)	/* largest defined AHB burst */
 #define AT91_DMA_CFG_FIFOCFG_ASAP	(0x2 << AT91_DMA_CFG_FIFOCFG_OFFSET)	/* single AHB access */
 
+
+/* ---------- XDMAC ---------- */
+#define AT91_XDMAC_DT_MEM_IF_MASK	(0x1)
+#define AT91_XDMAC_DT_MEM_IF_OFFSET	(16)
+#define AT91_XDMAC_DT_MEM_IF(mem_if)	(((mem_if) & AT91_XDMAC_DT_MEM_IF_MASK) \
+					<< AT91_XDMAC_DT_MEM_IF_OFFSET)
+#define AT91_XDMAC_DT_GET_MEM_IF(cfg)	(((cfg) >> AT91_XDMAC_DT_MEM_IF_OFFSET) \
+					& AT91_XDMAC_DT_MEM_IF_MASK)
+
+#define AT91_XDMAC_DT_PER_IF_MASK	(0x1)
+#define AT91_XDMAC_DT_PER_IF_OFFSET	(0)
+#define AT91_XDMAC_DT_PER_IF(per_if)	(((per_if) & AT91_XDMAC_DT_PER_IF_MASK) \
+					<< AT91_XDMAC_DT_PER_IF_OFFSET)
+#define AT91_XDMAC_DT_GET_PER_IF(cfg)	(((cfg) >> AT91_XDMAC_DT_PER_IF_OFFSET) \
+					& AT91_XDMAC_DT_PER_IF_MASK)
+
+#define AT91_XDMAC_DT_PERID_MASK	(0x7f)
+#define AT91_XDMAC_DT_PERID_OFFSET	(24)
+#define AT91_XDMAC_DT_PERID(perid)	(((perid) & AT91_XDMAC_DT_PERID_MASK) \
+					<< AT91_XDMAC_DT_PERID_OFFSET)
+#define AT91_XDMAC_DT_GET_PERID(cfg)	(((cfg) >> AT91_XDMAC_DT_PERID_OFFSET) \
+					& AT91_XDMAC_DT_PERID_MASK)
+
 #endif /* __DT_BINDINGS_AT91_DMA_H__ */